The 5th Asia Summer School and Symposium on Laser-plasma ...

CONTENTCONTENT ............................................................................................................................ 3AGENDA .............................................................................................................................. 5PROGRAM .......................................................................................................................... 7Laser science ....................................................................................................................... 9PIC simulation of LWFA <strong>and</strong> capillary discharge .............................................................. 10Basic issues on laser-plasma acceleration for novel versatile applications...................... 11Charged particle beam physics in laser-plasma acceleration ........................................... 12Concepts of laser plasma acceleration ............................................................................. 13Plasma based acceleration at UCLA: theory, simulation <strong>and</strong> experiment ........................ 14Advanced simulation tools for laser-plasma acceleration ................................................. 15Stability improvement of laser-accelerated electron beam <strong>and</strong> its control........................ 16Laser driven plasma wakefield accelerators <strong>and</strong> radiation sources ................................. 17Experiments <strong>and</strong> Diagnostics on Laser Particle Acceleration ........................................... 18Generation of fast electrons in the intense laser-plasma interactions .............................. 19Laser ion acceleration in laser-foil interaction ................................................................... 20Energetic ion generation by high contrast lasers irradiated on nanometer-foils ............... 21Particle acceleration by circularly polarized lasers ............................................................ 22Stable proton beam acceleration in two-ion-specie regime dominated by the laserradiation pressure .............................................................................................................. 23High harmonic x-ray sources ............................................................................................. 24Overview of high power THz sources from laser-plasma interaction ................................ 25Relativistic electrodynamics, synchrotron <strong>and</strong> undulator radiation ................................... 26An introduction to particle accelerators ............................................................................. 27An introduction to beam dynamics .................................................................................... 28THz region accelerator including beam driven dielectric acceleration .............................. 29Analytical method for laser plasma interaction .................................................................. 30Recent progress in laser wakefield acceleration experiments .......................................... 31Electron Bow-wave injection in laser wake field acceleration ........................................... 32Efficient energy coupling into nanolayed target by intense short-pulse laser ................... 333

9:00~11:00 Session VII11:00~11:30 Coffee breakConference room 2 st Floor11:30~12:30 Session VII12:30~13:30 Lunch 1 st Floor13:30~15:00 Session VIII Conference room 2 st Floor15:00~16:50 Lab. tour SIOM17:00~18:00 Coffee break <strong>and</strong> Poster 2 st Floor18:30~20:30 Banquet 1 st FloorAug. 20, 2010 Friday7:30~17:30 EXPO 2010 Waiting for the notice6

PROGRAMInvited lectures: 60 minutesInvited talks: 30 minutes or 15 minutesAug. 16Aug. 17Session IChairman: Hyyong Suk10:00~11:00 Laser science (Invited lecture) Prof. Leng11:30~12:30PIC simulation of LWFA <strong>and</strong> capillary discharge(Invited lecture)Prof. HurSession IIChairman: Dino Jaroszynski13:30~14:30Basic issues on laser-plasma acceleration fornovel versatile applications (Invited lecture)Prof. Nakajima14:30~15:30Charged-particle beam physics in laser-plasmaacceleration (Invited lecture)Prof. Suk16:00~17:00 Concepts of Laser Plasma (Invited lecture) Prof. Huang17:00~18:00Session III9:00~10:0010:00~11:0011:30~12:30Session IV13:30~14:3014:30~15:3016:00~17:0017:00~17:3017:30~17:4517:45~18:00Plasma based acceleration at UCLA: theory,Dr. Lusimulation <strong>and</strong> experimentn (Invited lecture)Chairman: Shigeo KawataAdvanced simulation tools for laser-plasmaDr. Cowanacceleration (Invited lecture)Stability improvement of laser-acceleratedDr. Kotakielectron beam <strong>and</strong> its control (Invited lecture)Laser-driven plasma wakefield accelerators <strong>and</strong>Prof. Jaroszynskiradiation sources (Invited lecture)Chairman: Hideyuki KotakiExperimental study on laser particlesProf. Guacceleration (Invited lecture)Generation of fast electrons in the intenseProf. Lilaser-plasma interactions (Invited lecture)Laser ion acceleration in lase-foil interactionProf. Kawata(Invited lecture)Energetic ion generation by high contrast laserProf. Yanirradiated on nanometer-foil (Invited talk)Particle acceleration by circularly polarizedDr. Wanglasers (Invited talk)Stable proton beam acceleration inDr. TongpuYutwo-ion-specie regime dominated by the laser7

adiation pressure (Invited talk)Aug. 18Aug. 19Session VChairman: Helmut Wiedemann9:00~11:00 High harmonic X-ray sources (Invited lecture) Prof. Nam11:30~12:30Session VI13:30~15:3016:00~18:00Session VII9:00~10:0010:00~11:0011:30~12:0012:00~12:30Session VIII13:30~14:0014:00~14:3014:30~15:00High power THz sources from relativistic laserProf. Shengplasmas (Invited lecture)Chairman: Zhengming ShengRelativisticelectrodynamics,synchrotron-radiation <strong>and</strong> undulator radiation Prof. Wiedemann(Invited lecture)An introduction to particle accelerators,historical review <strong>and</strong> basic physics (Invitedlecture)Prof. ZhangAn introduction to beam dynamics (Invitedlecture)Chairman: Chang Hee NamTHz region accelerator including beam drivenProf. Yoshidadielectric acceleration (Invited lecture)Analytical method for laser plasma interactionProf. Wei Yu(Invited lecture)Recent progress in laser wakefield accelerationDr. Hafzexperiments (Invited talk)Electron bow-wave Injection in laser wake fieldProf. Maacceleration (Invited talk)Chairman: Wei YuEfficient laser energy coupling bynanolayeredProf. Caotarget (Invited talk)Enhancement of electron injection using twoauxiliary interfering-pulses in LWFA (Invited Prof. Yintalk)Electron acceleration in wake bubble byultraintense laser interacting with plasma Prof. Xie(Invited talk)8

Laser scienceYuxin Leng(SIOM, CAS, China)9

PIC simulation of LWFA <strong>and</strong> capillary dischargeMin Sup HurKERI, Korea10

Basic issues on laser-plasma acceleration for novel versatileapplicationsKazuhisa NakajimaHigh Energy Accelerator Research Organization, Oho, Tsukuba, Ibaraki 305-0801 JapanDepartment of Physics, Shanghai Jiao Tong University, 200240, ChinaIn this decade, worldwide experimental <strong>and</strong> theoretical researches on laser-plasmaaccelerators have brought about great progress in high-energy high-quality electronbeams of the order of GeV-class energy <strong>and</strong> a few percent energy spread. On the otherh<strong>and</strong>, laser-driven production of GeV-class high-quality ion beams such as protons <strong>and</strong>carbon ions is underdeveloped, harnessing development of Petawatt-class ultra-intenselasers with high-quality <strong>and</strong> ultra-thin foil targets. <strong>The</strong>se high-energy high-quality particlebeams make it possible to open the door for a wide range of applications in research, <strong>and</strong>medical <strong>and</strong> industrial uses.In this lecture, basic issues on laser-driven plasma particle accelerators includingelectron- <strong>and</strong> ion-acceleration are reviewed from the aspects of injection or particlegeneration, acceleration process, resultant beam properties such as energy, energyspread, emittance, bunch length <strong>and</strong> charge, strictly determined by accelerationmechanism or laser-plasma interaction such as the bubble mechanism for electrons <strong>and</strong>radiation pressure acceleration for ions. Based on currently vital researches on laserplasma accelerators, we conceive novel versatile tools for broad scientific fields rangingfrom basic researches to medical <strong>and</strong> industrial applications in conjunction with the recentcutting-edge technology.11

Charged particle beam physics in laser-plasma accelerationHyyong SukAPRI, Gwangju Institute of Science <strong>and</strong> Technology Gwangju, 500-712 Rebuplic of KoreaIn laser-driven plasma acceleration, intense high-energy charged-particle beams aregenerated by strong laser-plasma interactions. Such beams are quite unique in severalpoints of view compared with those from RF-based conventional accelerators, <strong>and</strong>dynamics of charged particle beams is an interesting <strong>and</strong> important subject inlaser-plasma acceleration. In this lecture, some details of the beam dynamics inlaser-plasma acceleration are presented, which will be helpful for graduate students <strong>and</strong>young scientists.12

Concepts of laser plasma accelerationYen-Chieh HuangDepartment of Electrical Engineering, National Tsinghua University,Hsinchu 30013, Taiwan China13

Plasma based acceleration at UCLA: theory, simulation <strong>and</strong>experimentWei LuUniversity of California, Los Angeles (UCLA)<strong>The</strong> field of Plasma based acceleration (LWFA <strong>and</strong> PWFA) has experienced amazingdevelopment lately. During the past decade, Researchers at UCLA <strong>and</strong> their collaboratorshave achieved many important progresses on theory, simulation <strong>and</strong> experiment in bothLWFA <strong>and</strong> PWFA. In this lecture, I will describe some of these progress that I haveactively engaged in <strong>and</strong> try to give my personal view of this field. On theory part, the topicsI will cover include the nonlinear wake excitation in the blowout regime, beam loading,hosing instability, multi-dimensional injection (self <strong>and</strong> controlled) <strong>and</strong> phenomenologicalframework <strong>and</strong> scaling of LWFA in the blowout regime. On simulation part, the topics I willcover include the full scale 3D modeling of LWFA for GeV to 100GeV stage by large scaleparallel PIC simulations in both lab frame <strong>and</strong> in a Lorentz boosted frame. On experimentpart, the topics I will cover include both PWFA <strong>and</strong> LWFA. For PWFA, a series ofsuccessful experiments at SLAC will be discussed, including an experiment thatdemonstrated energy doubling of the 42GeV electron beam. For LWFA, a series ofexperiments at UCLA <strong>and</strong> LLNL will be discussed, including short pulse laser self-guiding,injection threshold, ionization induced injection <strong>and</strong> GeV level electron beam generation inthe self-guided blowout regime with both self <strong>and</strong> ionization induced injection.14

Advanced simulation tools for laser-plasma accelerationBenjamin M. Cowan 1 , David L. Bruhwiler 1 , John R. Cary 1,2 , Estelle Cormier-Michel 1,3 , EricEsarey 3 , Cameron G. R. Geddes 3 , Peter Messmer 1 , <strong>and</strong> Kevin Paul 11Tech-X Corporation, Boulder, Colorado 80303, USA2University of Colorado, Boulder, Colorado 80309, USA3Lawrence Berkeley National Laboratory, Berkeley, California 94720, USAAs the field of laser wakefield acceleration makes rapid progress, improved computationalmethods are essential to underst<strong>and</strong>ing the physics of the latest designs <strong>and</strong> furtherdeveloping the technology. We present an overview of recent advances in computationalalgorithms for laser-plasma acceleration.<strong>The</strong> use of higher-order particles inparticle-in-cell (PIC) simulations has been shown to significantly reduce numericalnoise. To simulate meter-scale stages, several algorithms have been developed,including operating in a Lorentz-boosted frame, scaling simulation parameters, <strong>and</strong>reduced models which remove the need to resolve the fast laser oscillations. Suchalgorithms can achieve over 5 orders of magnitude speedup over conventional PICsimulations. Finally, we discuss computation on emerging architectures, such asgraphics processing units, which can further speed simulations by two orders ofmagnitude.Work supported by U. S. Department of Energy, Office of Science, Office of High EnergyPhysics grants DE-SC0000840 (SBIR), DE-FC02-07ER41499 (ComPASS SciDAC), <strong>and</strong>DE-AC02-05CH11231 (LBNL), <strong>and</strong> by Tech-X Corporation.15

Stability improvement of laser-accelerated electron beam <strong>and</strong> itscontrolHideyuki KotakiJapan Atomic Energy AgencyLaser wakefield acceleration (LWFA) is regarded as a basis for the next-generation ofcharged particle accelerators. In experiments, it has been demonstrated that LWFA iscapable of generating electron bunches with high quality: quasi-monoenergetic, low inemittance, <strong>and</strong> a very short duration of the order of ten femtoseconds. Such femtosecondbunches can be used to measure ultrafast phenomena. In applications of the laseraccelerated electron beam, it is necessary to generate a stable electron beam <strong>and</strong> tocontrol the electron beam.In order to improve the stability <strong>and</strong> to control the electron beam, some methods areproposed. <strong>The</strong> proposed methods are colliding injection [1], ionization-stage control [2],etc. <strong>The</strong> colliding injection uses multiple laser pulses. A driver pulse produces a wakewave to accelerate electrons. Colliding laser pulses injects plasma electrons into the wakeexcited by the driver pulse. We can separate the wake wave excitation <strong>and</strong> the electroninjection. <strong>The</strong> separation makes possible to improve the electron-beam stability <strong>and</strong> tocontrol the electron beam. <strong>The</strong> ionization-stage control by using high-Z gases makes along channel due to cascade ionization. <strong>The</strong> long channel improves the stability of theelectron beam pointing.Experimentally, we have improved the electron beam stability by the optical injection <strong>and</strong>the ionization-stage control. In my lecture, I will present the improvement of the electronbeam stability, <strong>and</strong> its control of the direction <strong>and</strong> the profile.Reference1. E. Esarey et al., PRL 79, 2682 (1997); H. Kotaki et al., PoP 9, 1392 (2002); J. Faureet al., Nature 444, 737 (2006); H. Kotaki et al., PRL 102, 211083 (2009).2. M. Mori, et al., Phys. Rev. ST-AB 12, 082801 (2009).16

Laser driven plasma wakefield accelerators <strong>and</strong> radiation sourcesD. A. JaroszynskiUniversity of Strathclyde, Physics Department, John Anderson Building107 Rottenrow, Glasgow, G4 0NG, Scotl<strong>and</strong>, UKIn this lecture we will present progress towards producing an ultra-compact laser drivenplasma wakefield accelerator <strong>and</strong> applying it as an ultra-short pulse X-ray radiation source.We will discuss how the state-of-the-art before 2004, where electron beams wereproduced with 100% energy spreads, has been completely transformed by pioneeringdevelopments that have culminating in wakefield accelerators routinely producing veryhigh quality electron beams with energies from 50 MeV to more than 1 GeV. Anoverview of the basic physical processes of plasma wakefild acceleration will be given <strong>and</strong>we will examine how the transverse forces in the plasma bubble produced by the laserpulse cause oscillation of the electrons <strong>and</strong> result in the emission of brilliant X-ray pulses.We will also present an overview of applications of wakefield accelerators.17

Experiments <strong>and</strong> Diagnostics on Laser Particle AccelerationGu YuqiuNational Key Laboratory of Laser Fusion,Laser Fusion Research Center, CAEP, Mianyan, 621900Abstract: Laser particle acceleration, as an observable phenomenon of ultra intense laserinteracting with targets, is a fast increasing research field for its potential applications.Many theories <strong>and</strong> computer simulations were developed for describing laser particleacceleration <strong>and</strong> laser interacting with matter. Experiments <strong>and</strong> diagnostics are moreimportant from another point of view, since practice is the sole criterion for testing truth. Inthis report, the experiments on electron acceleration <strong>and</strong> proton acceleration on SILEX-Iwere introduced <strong>and</strong> the diagnostics used in the experiments were described in details.18

Generation of fast electrons in the intense laser-plasmainteractionsYutong LiInstitute of Physics, Chinese Academy of Sciences, Beijing 100080, ChinaEmail: ytli@aphy.iphy.ac.cnIn the interaction of a high intensity relativistic laser pulse with a solid foil, a large numberof electrons can be accelerated to very high energies, forming so-called fast electrons.Some of the fast electrons are ejected backward from the interaction region into thevacuum in front of the target. <strong>The</strong> others transport into the overdense plasma <strong>and</strong> coldtarget region <strong>and</strong>, finally, part of them escape from the rear target surface. <strong>The</strong> fastelectrons are of significance for fast ignition in inertial confined fusion, high-energy iongeneration, x-ray emission, etc. In this lecture the dependence of the fast electron beamson the experimental conditions of the laser <strong>and</strong> plasmas, such as intensity, polarization,incident angle, scale length of the preplasma, as well as the possible ways to control theemission direction of fast electrons will be discussed.Funding supported by the National Nature Science Foundation of China (Grant Nos. 10925421,10734130), National Basic Research Program of China (973 Program) (Grant No.2007CB815101) <strong>and</strong> the National High-Tech ICF program.19

Laser ion acceleration in laser-foil interactionShigeo KawataUtsunomya University, 321-8585 Utsunomiya Japan.kwt@cc.utsunomiya-u.ac.jpIn this lecture key issues relating to laser ion acceleration are summarized <strong>and</strong> explained withdetail examples. Intense short-pulse lasers are now available in actual experiments. <strong>The</strong> laserhas opened a new world in laser particle acceleration, radiation generation, etc. In laserthin-foil interaction first electrons are expelled or accelerated by the laser strong field, <strong>and</strong> forma strong electric field or a large current in the foil depending on the thin foil density <strong>and</strong> thefoil-parameter values. <strong>The</strong> high-energy-electron current or motion is sustained for the laserpulse length or a longer period than the laser pulse. During the period ions are graduallyaccelerated by the electric field, created by the high-energy electrons or the time-dependentstrong magnetic field. In the laser ion acceleration the following key issues are included: ionspecies control, ion energy control, ion divergence reduction, ion beam pulse shape control,energy spectrum control, laser-ion energy convergence enhancement, ion beam temperaturecontrol, ion particle number increase, etc.In the lecture the attendees are requested to propose or discuss new ideas to improve the ionbeam quality or to propose new directions for the laser ion acceleration. New solutions arevery welcome to solve the issues.Funding supported by JSPS, MEXT, CORE (Center for Optical Research <strong>and</strong> Education) <strong>and</strong>ILE / Osaka university, Japan.<strong>The</strong> Author would like to extend his acknowledgements to colleagues <strong>and</strong> friends, including Dr.Y.Y. Ma, Dr. W.M. Wang, Prof. Z.M. Sheng, Prof. Y.T. Li, Dr. Q. Kong, Dr. P.X. Wang, Prof. J.Limpouch, Dr. O. Klimo, Prof. A.A. Andreev, Dr. K. takahashi, Dr. D. Barada <strong>and</strong> Dr. D. Satoh.20

Energetic ion generation by high contrast lasers irradiatedon nanometer-foilsX.Q.YanState Key Lab. of Nuclear Physics & Technology, PKU, Beijing 100871, ChinaMax Planck for Quantum Optics (MPQ), Garching B. Muenchen, 85748, GermanyUltrahigh-intensity lasers can produce accelerating fields of TV/m, surpassing those inconventional accelerators for ions by few orders of magnitude. Remarkable progress hasbeen made in producing laser-driven ultra-bright MeV proton <strong>and</strong> ion beams in a verycompact fashion compared to conventional RF accelerators. <strong>The</strong>se beams have beenproduced up to several MeV per nucleon with outst<strong>and</strong>ing properties in terms oftransverse emittance <strong>and</strong> current, but typically suffer from exponential energydistributions.A new mechanism for laser-driven ion acceleration was proposed, where particles gainenergy directly from the Radiation Pressure Acceleration or Phase Stable Acceleration(RPA / PSA). By choosing the laser intensity, target thickness, <strong>and</strong> density such that theradiation pressure equals the restoring force given by the charge separation field, the ionscan be bunched in a phase-stable way <strong>and</strong> efficiently accelerated to a higher energy. Inproof of principle experiments quasi-monoenergetic peaks for C 6+at ~30 MeV wereobserved by MPQ/MBI/LANL/PKU group <strong>and</strong> C6 +at >500 MeV (exponential) wasobserved at LANL/MPQ. Furthermore at LANL also quasi-monoenergetic protons at~40MeV were generated from nm thin diamond-like carbon foils. <strong>The</strong>oretical study showsthat the required medical proton/carbon beams (200MeV for proton <strong>and</strong> 400MeV/u forCarbon) can be generated from hydrogen/carbon foil (sub micron) in a laser intensity of~10 21 /10 22 W/cm 2 .Funding supported by NSFC (10935002)21

Particle acceleration by circularly polarized lasersW.-M. Wang 1,2 , Z.-M. Sheng 1,3 , S. Kawata 2 , Y.-T. Li 1 , L.-M. Chen 1 , J. Zhang 1,31 Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing100190, China2 Graduate <strong>School</strong> of Engineering, Utsunomiya University, 7-1-2 Yohtoh, Utsunomiya 321-8585,Japan3 Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, Chinahbwwm1@aphy.iphy.ac.cn<strong>The</strong> first part is concerned with the electron acceleration by a circularly polarized laserpulse. Our analytical <strong>and</strong> simulation investigations show that future ultra-short 10 22 -10 25Wcm -2 laser pulses offer the possibility of producing ultra-short monoenergetic electronbeams in the GeV-TeV level by direct laser ponderomotive force acceleration (LPFA) indistances of millimeters to about one meter. A scheme is proposed that a thin solid foil<strong>and</strong> a thick solid foil are placed on the laser axis, where the thin foil supplies the electronsource for LPFA <strong>and</strong> the thick foil reflects the laser away while allows the acceleratedelectrons to go through. By optimizing the distance between the foils, one can obtain themaximum electron beam energy. This scheme is demonstrated by particle-in-cellsimulations. In such laser regime, LPFA has the larger acceleration field <strong>and</strong> can producehigher energy electron beams than laser wakefield acceleration (LWFA).Such laser can also be used to accelerate ions. <strong>The</strong> acceleration of protons by theradiation pressure of a circularly polarized laser pulse with the intensity up to 10 21 Wcm -2from a double-layer or multi-ion-mixed thin foil is investigated by two-dimensionalparticle-in-cell simulations, where the double-layer foil is composed of a heavy ion layer<strong>and</strong> a proton layer. It is found that the radiation pressure acceleration can be classifiedinto three regimes according to the laser intensity due to the different critical intensities forlaser transparency with different ion species. When the laser intensity is moderately high,the laser pushes the electrons neither so slowly nor so quickly that the protons can catchup with the electrons, while the heavy ions cannot. <strong>The</strong>refore, the protons can beaccelerated efficiently. <strong>The</strong> proton beam generated from the double-layer foil has betterquality <strong>and</strong> higher energy than from a pure proton foil with the same areal electron density.When the intensity is relatively low, the protons <strong>and</strong> heavy ions are accelerated together,which is not favorable to the proton acceleration. When the intensity is relatively high,neither the heavy ions nor the protons can be accelerated efficiently due to the lasertransparency through the target.22

Stable proton beam acceleration in two-ion-specie regimedominated by the laser radiation pressureTongpu YuInstitut fuer <strong>The</strong>oretische Physik I, HHUD, 40225 Duesseldorf, GermanyRecently, with the rapid development of laser technology, one of the most straightforwardacceleration mechanisms, radiation pressure acceleration (RPA) is being re-visited. Byusing multi-dimensional particle-in-cell simulations, we investigate the proton accelerationdominated by the RPA in a two-ion-specie ultra-thin foil. In this two-ion-specie regime, thelighter protons are initially separated from the heavier carbon ions due to their highercharge-to-mass ratio Z/m. <strong>The</strong> laser pulse is well-defined so that it doesn’t penetrate thecarbon ion layer. <strong>The</strong> Rayleigh-Taylor-like (RT) instability seeded at the very early stagethen only degrades the acceleration of the carbon ions which act as a ”cushion” for thelighter protons. In the absence of proton-RT instability, the produced high qualitymono-energetic proton beams can be well collimated even after the laser-foil interactionconcludes.23

High harmonic x-ray sourcesChang Hee NamDepartment of Physics <strong>and</strong> Coherent X-ray Research Center, KAIST, Daejeon 305-701, Koreachnam@kaist.ac.krGaseous atoms, exposed to an intense femtosecond laser field, are periodicallymodulated by the laser electric field <strong>and</strong> emit very high-order harmonics of the laserfrequency. <strong>The</strong> high harmonics possess unique properties of superb spatial coherence<strong>and</strong> ultrashort duration reaching the attosecond range. In this lecture the physical pictureof high harmonic generation processes will be given first, <strong>and</strong> the characteristics of highharmonics <strong>and</strong> applications to x-ray interferometry <strong>and</strong> to attosecond pulse generation willthen be explained.24

Overview of high power THz sources from laser-plasma interactionZ.M. ShengDepartment of Physics, Shanghai Jiao Tong University, Shanghai 200240, ChinaInstitute of Physics, Chinese Academy of Sciences, Beijing 100190, ChinaEmail: zmsheng@sjtu.edu.cn<strong>The</strong> high intensity laser-plasma can be a radiation source covering ultra-broad spectrumranging from terahertz (THz) radiation to MeV gamma ray. In this talk, I will present anoverview of recent experimental, theoretical <strong>and</strong> numerical studies on THz emission fromlaser-plasma interaction. Particular attention will be paid on the progress made in ourgroup.Experimental investigation of strong THz wave generation by laser interacting with solidtargets has been conducted. It is found that such emission is in p-polarization <strong>and</strong> itsenergy scales linearly with the incident laser energy. <strong>The</strong> emission shows very boardspectrum such as 20THz. It is attributed to the plasma currents associated with the hotelectrons produced by the laser pulse.In a theoretical study, it is found that high power THz emission can be produced by theresidual currents as a laser pulse passing through a gas or plasma target. <strong>The</strong> residualcurrents can be produced by field ionization process or by a dc/ac bias field applied overtenuous plasma, which is produced by a laser pulse. <strong>The</strong> current can be convertedefficiently into electromagnetic (EM) emission at the plasma frequency p with itsamplitude <strong>and</strong> polarization determined by the bias. <strong>The</strong> initial phase of the EM waves canbe controlled by the triggering time of the bias <strong>and</strong> therefore circularly/elliptically polarizedEM waves can be obtained by applying two bias fields perpendicular to each other. Ananalytical model is presented <strong>and</strong> confirmed by particle-in-cell (PIC) simulation.In another theoretical study, we clarify THz radiation mechanism from a plasma filamentformed by an intense femtosecond laser pulse based upon 2D PIC simulation. <strong>The</strong>nonuniform plasma density of the filament formed by field ionization <strong>and</strong> the electronmotion driven by the laser ponderomotive force can result in a nonvanishing radiatingcurrent for the THz radiation. This current is mainly located within the pulse <strong>and</strong> the firstcycle of the wakefield of the laser pulse. As the laser pulse propagates, a single-cycle <strong>and</strong>radially polarized THz pulse is constructively built up forward.25

Relativistic electrodynamics, synchrotron <strong>and</strong> undulator radiationHelmut WiedemannStanford UniversityIn this lecture, we discuss the emission of electromagnetic radiation from relativisticelectron beams. Starting with fundamental rules determining the possibility to emitelectromagnetic radiation from charged particles, we derive the radiation power fromdipole oscillations of electrons. Applications of four-vectors will define the emissiongeometry <strong>and</strong> relativistic Doppler effect which together with the Lorentz contraction playsan important role in the final radiation spectrum. Transforming that to the laboratorysystem we are ready to derive the spectrum of synchrotron radiation. Special insertiondevices like wavelength shifters, undulators <strong>and</strong> wiggler magnets have been developed tocontrol the radiation properties without affecting the electron beam in the storage ring.Undulator magnets emit quasi monochromatic radiation in a line spectrum, while radiationfrom wiggler magnets produces a more <strong>and</strong> more dense line spectrum overlapping at highharmonics into a continuous spectrum similar to that of a bending magnet.26

An introduction to particle acceleratorsChuang ZhangInstitute of High Energy Physics, CAS, Beijing 100049, China<strong>The</strong> human’s curiosity on the universe has always been the driven force behind thedevelopment of telescopes <strong>and</strong> microscopes. As a type of powerful microscope, particleaccelerators play an important role in discovery on the micro-world, which provide a majorstimulus for research into the constituents <strong>and</strong> nature of matter. Traced to its three roots,the history of accelerators is a continuous upgrade towards higher energy, betterperformance <strong>and</strong> wider application. Innovative ideas, new methods, <strong>and</strong> new technologiesemerge in endlessly. Historical evolution, innovative ideas <strong>and</strong> prospective in acceleratordevelopments are briefly reviewed in this lecture.• <strong>The</strong> outline of the lecture is as follows:• From telescope to microscope• Historical evolution of accelerators• Frontiers of modern accelerators• Future science <strong>and</strong> accelerators• Summary27

An introduction to beam dynamicsChuang ZhangInstitute of High Energy Physics, CAS, Beijing 100049, ChinaBeam dynamics is the study of particle beams, their motion in environments, involvingexternal electro-magnetic fields <strong>and</strong> their interactions, including the interaction of beamswith matters, of beams with beams, <strong>and</strong> of particle beams with radiation. Evolving fromconcepts <strong>and</strong> ideas derived from classical mechanics, electromagnetism, statisticalphysics, <strong>and</strong> quantum physics. <strong>The</strong> study of beams is opening up a very rich field, withnew effects being discovered <strong>and</strong> new types of beams with novel characteristics beingrealized. Basic knowledge of the beam physics is briefly introduced in this lecture for thestudents who are preparing to work in the field of laser-plasma acceleration <strong>and</strong> radiation.<strong>The</strong> outline of the lecture is as follows:• Basic Concepts• Transverse Motion• Longitudinal Motion• Collective Effects• Lepton <strong>and</strong> Hadron28

THz region accelerator including beam driven dielectricaccelerationMitsuhiro YoshidaHigh Energy Accelerator Research Organization (KEK) in JapanHigher frequency electromagnetic wave can make much higher energy density that leadsvery high electric field. <strong>The</strong> electric field is expected to increase linear to the frequency.<strong>The</strong> terahertz (THz) region accelerator is growing to become a moderate frequency regionto accelerate the recent low emittance <strong>and</strong> short bunch electron beam. For example, thetransverse beam size can be easily focused under 10 micron using the low emittancebeam <strong>and</strong> the bunch length can be compressed under 100 fs using a photo cathode or abunch compressor. Thus the transverse <strong>and</strong> longitudinal beam size becomes enoughsmall to capture inside the stable phase space.However such a THz region accelerator is not currently established since the THz sourceis limited <strong>and</strong> some additional solution is required to avoid the wakefield <strong>and</strong> the surfacebreakdown.In this lecture, some c<strong>and</strong>idates of the THz accelerator, its sources <strong>and</strong> simulationmethods are presented.29

Analytical method for laser plasma interactionWei Yu(SIOM, CAS, China)30

Recent progress in laser wakefield acceleration experimentsNasr A. M. HafzAPRI, Gwangju Institute of Science <strong>and</strong> Technology, Gwangju 500-712, KoreaRelativistic electron beam generation through the excitation of large-amplitude plasma waves byhigh-power ultrashort laser pulses has gained a lot of attention in the past few years. Such anacceleration regime is known as the laser wakefield accelerator (LWFA) [1]. In 2004 a breakthroughin LWFA research has led, for the first time, to the generation of high-quality quasimonoenergeticelectron beams [2-4]. Since then, several important results have been reported in this field [5-7].With the emergence of compact PW-class <strong>and</strong> PW laser systems around the world, a new era for theLWFA research has started [8-9]. By using PW-class lasers, laser-driven plasma acceleration isforeseen to produce multi- GeV electron beams in the near future. One of the main goals for futureLWFA research would be achieving electron energy frontiers relevant to high-energy physicsapplications [10]. However, there are other motivations for laser-driven electron beam accelerationresearch. For example, electron beams from laser-driven plasma (shortened here as EBLP)produced by using 10−20 TW laser systems are very useful from the application point of view [11].EBLP are unique in their characteristics as they have a small divergence of a few mrad <strong>and</strong> anextremely-short bunch length of ≈ 40 fs [12] or shorter. Those characteristics are essential forcompact high brightness light source applications such as free-electron lasers <strong>and</strong> synchrotrons[13-14]. In addition, EBLP are naturally synchronized with the driving laser pulse, thus allowingjitter−less timing for pump-probe experiments <strong>and</strong> laser-electron collisions for Thomson scatteringX-ray applications. Furthermore, high flux EBLP in the 20 MeV-range have been used in table-topphotonuclear physics <strong>and</strong> radiation chemistry experiments [15-16]. In this talk, I am going to reviewthe recent progress of LWFA in key laboratories worldwide <strong>and</strong> present recent results from mylaboratory [17].Reference1. T. Tajima <strong>and</strong> J. Dawson, Phys. Rev. Lett. 43 (1979) 267.2. S. P. D. Mangles et al., Nature, 431, (2004) 535.3. C. G. R. Geddes, et al., Nature, 431, (2004) 538.4. J. Faure et al., Nature 431 (2004) 541.5. J. Faure et al., Nature 444 (2006) 737.6. W. Leemans et al., Nature Phys. 2 (2006) 696.7. Nasr A. M. Hafz et al., Nat. Photonics 2 (2008) 571.8. S. Kneip et al., Phys. Rev. Lett. 103 (2009) 035002.9. D. H. Froula et al., Phys. Rev. Lett. 103 (2009) 215006.10. S. F. Martins et al., Nat. Phys. 6 (2010) 311.11. Compact 10−20 TW laser systems are affordable to many university-scale laboratoriesworldwide.12. 12 A. D. Debus et al., Phys. Rev. Lett. 104 (2010) 084802.13. H.-P. Schlenvoigt et al., Nat. Phys. 4 (2008) 130.14. Matthias Fuchs et al., Nat. Phys. 5 (2009) 826.15. A. Giulietti etal., Phys. Rev. Lett. 101 (2008) 105002.16. Beata Brozek-Pluska et al., Rad. Phys. & Chem. 72 (2005) 149.17. Nasr A. M. Hafz et al., Accepted 2010.31

Electron Bow-wave injection in laser wake field accelerationY. Y. Ma 1,2,3 S. Kawata 3 Y. Q. Gu 2 Z. M. Sheng 4 M. Y. Yu 5 H. J. Liu 2 H. B. Zhuo 6 W. M. Wang 3,7Y. Yin 1 K. Takahashi 3 X. H. Yang 1 C. L. Tian 1 <strong>and</strong> F. Q. Shao 11. Department of Physics, National University of Defense Technology, Changsha 410073, China2. Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621000, China3. Center for Optical Research <strong>and</strong> Education, Graduate <strong>School</strong> of Engineering, Utsunomiya University,7-1-2 Yohtoh, Utsunomiya 321-8585, Japan4. Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China5 Institute for Fusion <strong>The</strong>ory <strong>and</strong> Simulation, Department of Physics, Zhejiang University, Hangzhou310027, China6. College of Computer Science, National University of Defense Technology, Changsha 410073, China7. Institute of Physics, Chinese Academy of Sciences, Beijing 100080, ChinaA new regime of strong electron injection named electron bow-wave injection (EBWI) inlaser wakefield acceleration of electrons is investigated using particle-in-cell simulation. Incontrast to the known injection regimes, here the dense trapped electrons in a strongelectron bow wave (EBW) excited behind the primary bubble contribute most to theinjected, trapped, <strong>and</strong> accelerated electrons in the bubble. EBWI operates at higher laserintensities than that of the normal self injection (NSI) of the electrons from the bubbleperiphery. Even with EBWI for lower laser intensities, the number of the bubble-trappedelectrons is much larger than that from NSI. In this regime the electrons in the intenseelectron bow waves behind the first bubble catch up with the bubble tail <strong>and</strong> enter into it.<strong>The</strong> number of the bubble-trapped electrons can thus be much enhanced. It is shown thatthe trapped-electron charge can reach 0.27 nC in 180μm. A simple analytical model of thecondition for EBWI is proposed, which is in good agreement with the simulation results.<strong>The</strong> EBWI scheme is robust <strong>and</strong> controllable <strong>and</strong> should be useful for efficient generationof collimated high energy electrons.Funding supported by the National Natural Science Foundation of China (grants 10976031,10935002, <strong>and</strong> 10835003) <strong>and</strong> the National Basic Research Program of China (grants2007CB815105 <strong>and</strong> 2008CB717806). Y. Y. Ma acknowledges the support of the JSPS <strong>and</strong>CORE of Utsunomiya University, Japan32

Efficient energy coupling into nanolayed target by intenseshort-pulse laserLihua CaoInstitute of Applied Physics <strong>and</strong> Computational Mathematics, Beijing 100088, ChinaCenter for Applied Physics <strong>and</strong> Technology, Peking University, Beijing, 100871, China<strong>The</strong> introduction of a target with nanolayered front can reduce the reflection <strong>and</strong> increaseenergy coupling of an intense short laser pulse into it. <strong>The</strong> electrons within the skin depthon the target surfaces are accelerated to relativistic velocities <strong>and</strong> then propagate forwardwith most of the absorbed laser energy along the surfaces of the layers. <strong>The</strong> twodimensional particle-in-cell (PIC) simulations show that more laser energy goes intokinetic energy of hot electrons respected to the planar target. <strong>The</strong> energy absorptiondecreases a little both for too lower <strong>and</strong> higher laser intensity. It is ascribed to theweakening of the electric <strong>and</strong> magnetic fields associated with smaller hotelectron jet, shorter relativistic skin length at lower intensity <strong>and</strong> the corruption oflayer structure at higher intensity. <strong>The</strong> manipulation of the properties of the hotelectrons is discussed by matching the parameters of nanolayered target <strong>and</strong> laser pulse.33

Enhancement of electron injection using two auxiliaryinterfering-pulses in LWFAZ. Y. Ge 1 Y. Yin 1* H. Xu 2, 3 Y. Y. Ma 1, 3 H. B. Zhuo 2 <strong>and</strong> F. Q. Shao 11 Department of Physics, National University of Defense Technology, Changsha 410073,China2 National Laboratory of Parallel <strong>and</strong> Distributed Processing, National University of DefenseTechnology, Changsha 410073, China3 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621000,China*yinyansilver@hotmail.comAn interfering-pulses auxiliary laser wake-led acceleration (IPA-LWFA) scheme has beenpro-posed <strong>and</strong> examined by particle-in-cell (PIC) simulations. In this scheme, twolow-intensity long pulses are interfering in the plasma before the main pump pulse arrival.<strong>The</strong> plasma density is modulated in the interfering ¯eld of the auxiliary pulses <strong>and</strong> theelectrons are heated slightly. Enhancement of electron injection has been demonstratedcompared with the LWFA. It is shown that the IPA-LWFA works well for the main pumppulse with moderate intensity I < 1021W=cm2. When the pump pulse is extremely intense,the energy distribution of electrons is broadened although the number of injectedelectrons increases.34

Electron acceleration in wake bubble by ultraintense laserinteracting with plasmaBai-Song Xie <strong>and</strong> Hai-Cheng WuCollege of Nuclear Science <strong>and</strong> Technology, Beijing Normal University, Beijing 100875 ChinaEmail: bsxie@bnu.edu.cnModification of fields <strong>and</strong> shape of bubble from electrons which go into the bubble interiorfrom the bubble front is theoretically studied by three different models - thephenomenological theory from Kostyukov et al. [Phys. Plasmas 11, 5256 (2004)], a modelwith an elliptic boundary condition <strong>and</strong> the consistent dynamic model from Lu et al.[ Phys.Plasmas 13, 056709 (2006)]. <strong>The</strong> results from these three models are the same: theelectrons in the bubble go backward with a speed close to the velocity of light in vacuum,the slops of the transverse fields are reduced by these electrons, <strong>and</strong> the ratio of theradius of longitudinal to transverse of the bubble is decreased; the slop of the longitudinalelectric field is hardly changed because the decrease of the radius’ ratio compensates theweakening of the field by the electrons. <strong>The</strong> theoretical results of field <strong>and</strong> bubble shape inmodification would agree better with the particle-in-cell simulations.A way of optimizing the electron acceleration in the wake bubble - a quasi phase-stableacceleration scheme - is also presented. This way is achieved by adding a capillary-likedense-plasma wall with an inner radius of between the initial lateral radius <strong>and</strong> maximumlateral radius of the bubble in the path of the laser pulse. With the wall, the bubble shapeis transversely controlled <strong>and</strong> longitudinally shrunk. <strong>The</strong> advantages of this scheme are asfollows: (i) <strong>The</strong> shrink of the bubble sheath would tailor some of the injected electronbunch <strong>and</strong> suppress further electron self-injection, this results in a more monoenergeticelectron bunch; (ii) <strong>The</strong> accelerated electron bunch almost always stays close to thebottom of the bubble that leads to larger average accelerating gradient <strong>and</strong> overcomes thelimit of dephasing to a certain degree; (iii) This scheme does not need increase thedensity of the plasma <strong>and</strong> the depletion rate of the laser, however, it does produce alarger gradient of accelerating field. <strong>The</strong>refore, in this scheme, the electron bunch isaccelerated to much higher energy, meanwhile, it has narrower energy spread.35

Electron-positron pair creation in time-dependent external fieldsNa Ren, Jia-xiang WangState Key Laboratory of Precision Spectroscopy, Department of Physics, East China NormalUniversity, Shanghai, 200062 ChinaWe investigate electron-positron pair production from vacuum for time-dependent laserpulses. It has been found that, in order to have prominent pair productions, we not onlyrequire that the electric field intensity should be higher than the Schwinger threshold, butalso require that the pulse duration should be longer than a threshold. <strong>The</strong> formercondition guarantees that the electron in the negative energy state could gain enoughenergy to jump onto a positive-energy state in Compton time. <strong>The</strong> latter is related tomomentum requirement for the transition. In particular, we show that the probability of thecreated electron-positron pairs depends on the laser frequency, the pulse length, <strong>and</strong> thecarrier phase. This observation could help in the design of laser pulses to optimize theexperimental signature of Schwinger pair production.Funding supported by Shanghai Shuguang Project Grant personnel issues(06sg27); ShanghaiPujiang Talent Project Grant subject (07pj14036); National Natural Science Foundation oftopics (10974056).36

Comparison of ion acceleration from ultra-short intense laserinteractions with thin foil <strong>and</strong> small dense targetYouwei TianCollege of Science, Nanjing University of Posts <strong>and</strong> Telecommunications,Nanjing 210003, China<strong>The</strong> generation of highly directional beam of ions with energies in the MeV range throughthe interaction of high-intensity laser radiation with solid targets, gas jets, <strong>and</strong> clusters hasbeen the subject of great significance due to recent research in high-field laser interactionphysics by experiments <strong>and</strong> particle-in-cell (PIC) simulations. Laser-driven energetic ionbeam generation has a promising application in hadron cancer therapy, as well as incontrolled nuclear fusion <strong>and</strong> particle injectors. In a number of experimental <strong>and</strong>theoretical publications, the laser-driven ion beam generation with energies in the range offew MeV to several tens of MeV has been reported.<strong>The</strong> comparative efficiency <strong>and</strong> beam characteristics of high-energy ions generated fromthe interaction of a petawatt laser pulse with thin foil target <strong>and</strong> a small solid-densityplasma bunch target have been studied by particle-in-cell simulation under identicalconditions. It is shown that thin foil <strong>and</strong> small solid dense target of micrometer size can be21 2efficiently accelerated when irradiated by a laser pulse of intensity > 10 W / cm . Usingdirect beam measurements, we find that small solid dense target acceleration produceshigher energy particles with smaller divergence <strong>and</strong> a higher efficiency compared to thinfoil target acceleration. <strong>The</strong> merits of small solid target acceleration can be exploited forpotential applications such as its role as ignitor for fast ignition (FI) in inertial confinementfusion (ICF).This work has been supported by the National Natural Sciences Foundation of China underGrant No. 10947170/A05, <strong>and</strong> Foundation of NJUPT under Grant Nos. NY207151 <strong>and</strong>NY207006.37

Interferometric technique for measurement of capillary plasmadensityDong K. Jang, Do G. Jang, Min-Seok Kim, Seong Y. Oh1), <strong>and</strong> Hyyong SukGraduate Program of Photonics <strong>and</strong> Applied Physics, Gwangju Institute of Science <strong>and</strong>Technology, Gwangju 500-712, Republic of Korea1)Advanced Photonics Research Institute, Gwangju Institute of Science <strong>and</strong> Technology,Gwangju 500-712, Republic of KoreaLWFA (laser wake field acceleration) has been extensively studied to achieve high energyelectron beams in a short distance compared to conventional accelerators. Recently apre-ionized plasma capillary apparatus has been utilized in order to accelerate electronsup to Gev level, avoiding the rapid laser divergence due to diffraction. Such an opticalphenomenon can be avoided with the so-called ‘optical guiding’, where the laser beamcan propagate a long distance due to the parabolic density profile. In this case,divergence of the laser beam can be compensated by the focusing effect from theparabolic density profile. <strong>The</strong> plasma column in the capillary changes very rapidly in time,so knowing the density profile dynamics is very important. Shadowgraphy <strong>and</strong>interferometry are good techniques to measure the temporal <strong>and</strong> spatial electron density.We built a Mach-Zehnder interferometer to investigate the plasma dynamics in thecapillary <strong>and</strong> some results are shown in this presentation.38

Detection of the terahertz radiation emitted from laser-inducedplasmas by using the electro-optic sampling methodDo-Geun Jang, Jin-Ju Kim, <strong>and</strong> Hyyong SukGraduate Program of Photonics <strong>and</strong> Applied Physics, Gwangju Institute of Science <strong>and</strong>Technology, Gwangju 500-712, Republic of KoreaTHz radiation based on laser-induced plasma was first demonstrated by Hamster et al,<strong>and</strong> the THz pulse emission process in air has been studied by a few people so far. Whenan intense laser pulse is focused in air, it produces a plasma <strong>and</strong> it propagates through it.In this case, the electrons in the plasma oscillate at the frequency of ,where is the density of electrons, is the electric charge, is the mass of theelectron, <strong>and</strong> is the permittivity of the free space. In the density region of 1016 – 1018cm-3, the plasma frequency is sub-1012 Hz range <strong>and</strong> we are interested in this range. Inour research group at GIST, we are going to generate THz pulses from an ionized airplasma using an intense laser beam. We are also interested in application of the THzemission for diagnostics of the plasma. For this research we are going to use aTi:sapphire laser system consisting of an oscillator <strong>and</strong> a regenerative amplifier. <strong>The</strong> laserpulse will be focused in air by means of a parabolic mirror <strong>and</strong> the air pressure will becontrolled in the gas cell to investigate the relation between the THz spectrum <strong>and</strong> theplasma density, which can give a way for plasma diagnostics. For the THz detectionsystem, the produced THz pulses from the plasma will be measured by the electro-opticsampling(EOS) method in time-domain. In this presentation, we will show the on-goingexperiment for THz generation <strong>and</strong> detection from the laser-induced plasmas.39

Overloading Effect of Energetic Electrons on Wakefield in BubbleRegimeJiancai Xu, Baifei Shen, Xiaomei Zhang, Meng Wen, Liangliang Ji, Wenpeng Wang,Yahong YuState Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics <strong>and</strong> FineMechanics, Chinese Academy of Sciences, Shanghai 201800, ChinaOverloading effects of a high-charge self-injected electron bunch on bubble wakefieldhave been studied in the bubble regime. After many electrons has been trapped by thebubble, the wakefield is strongly modified <strong>and</strong> prevents further injection of backgroundelectrons. <strong>The</strong>se effects are directly observed in two-dimensional particle-in-cellsimulations, <strong>and</strong> are explained by one-dimensional wake theory. In order to obtain muchmore energetic electrons, it is suggested to use a decreasing density profile of the plasmain the electron acceleration process.40

Photodissociation of nitrobenzene <strong>and</strong> o-nitrotoluene at 266 nm: anew photoproduct of OHXian-Fang Yue 1,2 , Hai-Ran Feng 1 , Jie Cheng 11 Department of Physics <strong>and</strong> Information Engineering, Jining University, Qufu 273155, China2 State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics,Chinese Academy of Sciences, Dalian 116023, ChinaPhotodissociation of nitrobenzene <strong>and</strong> o-nitrotoluene has been investigated in the gasphase at room temperature at 266 nm. <strong>The</strong> OH fragment was firstly observed in thephotodissociation of nitrobenzene. <strong>The</strong> internal state distribution of the nascent OH fromthe photodissociation of nitrobenzene <strong>and</strong> o-nitrotoluene were measured using theone-photon laser induced fluorescence (LIF) technique. It was found that the OH fragmentwas vibrationally cold <strong>and</strong> their rotational state distributions showed Boltzmann behavior.Preferential populations of the 2Π3/2 spin-orbit state <strong>and</strong> the Π+ Λ-doublet state wereobserved for the two molecules. One possible dissociation mechanism involving theintramolecular hydrogen transfer from the benzene ring to the nitro group was proposedfor the OH fragment pathway. To examine the nature of the potential energy surfaces, weperformed the density functional theory (DFT) calculations for the hydrogen transfer <strong>and</strong>dissociation processes on both T1 <strong>and</strong> S0 states.Funding supported by National Natural Science Foundation of China (No.10947103), theFoundation for Outst<strong>and</strong>ing Young Scientist in Sh<strong>and</strong>ong Province (No.2008BS01017), <strong>and</strong>the Young Funding of Jining University (No.2009QNKJ02).41

Raman amplification of ultrashort laser pulses in plasmaX. Yang G. Vieux E. Brunetti J. Farmer B. Ersfeld D.A. JaroszynskiUniversity of Strathclyde, Dept of Physics, 107 Rottenrow, Glasgow UKRaman backscattering (RBS) in plasma is an attractive source of intense, ultrashort laserpulses which has the potential to bring in a new generation of laser amplifiers. Capitalizingon the advantages of plasmas, which can withst<strong>and</strong> extremely high power densities <strong>and</strong>can offer high efficiencies over short distances, Raman amplification in plasma could leadto significant reductions in both size <strong>and</strong> cost of high power laser systems.We are investigating chirped laser pulse amplification through RBS in the linear <strong>and</strong>nonlinear regimes, with experiments aiming to develop an effective way to transfer energyfrom a long pump pulse to a resonant counter-propagating short probe pulse. Currentresults show a peak spectral gain of 2200%, with an energy increase of 500%.Funding supported by University of Strathclyde42

Quasi-monoenergetic proton acceleration from double layer targetsirradiated by intense laser pulseL. G. Huang, A. L. Lei*, Y. Bai, Wei Yu <strong>and</strong> M.Y. YuShanghai Institute of Optics <strong>and</strong> Fine Mechanics, CAS, Shanghai 201800, ChinaInstitute for Fusion <strong>The</strong>ory <strong>and</strong> Simulation, Zhejiang University, Hangzhou 310027, China*E-mail: lal @siom.ac.cnAbstract: In recent ten years, laser-ion acceleration has been studied with a great interestworldwide. Double layer targets (DLT) consisting of a high-Z layer <strong>and</strong> a low-Zhydrogen-rich layer was first proposed by Ueshima et al. to obtain higher-energy protonsrelative to a single layer target. Bulanov et al. <strong>and</strong> Esirkepov et al. found in a particle in cellsimulation that high-quality, i.e., monoenergetic, intense ion beam could be achieved withDLT. Schwoerer et al. experimentally demonstrated laser acceleration of protons with aquasi-monoenergetic peak distribution using DLT. In this paper, an improved DLT isproposed to enhance monoenergetic proton acceleration with higher peak energycompared to the conventional DLT. <strong>The</strong> shape of improved DLT is shown in Fig.1(b). <strong>The</strong>front layer of the both DLTs is made of Au 2+ ions <strong>and</strong> the rear is a thin proton patch. Whenthe intense laser pulse irradiates onto the two DLTs, one sees that the laser absorption<strong>and</strong> the hot electron temperature are both higher in the case of the improved target. As aresult, the protons can be accelerated more efficiently by the rear-surface electrostaticsheath field. As shown in Fig.1(c), the protonenergy spectra show a higher peak energy~77.1MeV with the improved DLT while thepeak energy of the reference target is57.2MeV.FIG.1. Shape of the (a) conventional DLT; (b)improved DLT; <strong>and</strong> (c) energy spectra of theimproved DLT <strong>and</strong> conventional DLT at t=42T.43

Comparison between classical <strong>and</strong> quantum treatment of harmonicgeneration by relativistic electrons in strong laser fieldsA.K. Li <strong>and</strong> J. X. WangDepartment of Physics, East China Normal University, ShanghaiWe consider relativistic harmonic generation by scatting of circularly <strong>and</strong> a linearlypolarized laser field from free electron. We investigate in detail the relation between thephoton spectrum calculated through classical <strong>and</strong> quantum theory for several scatteringconfigurations by both analytical <strong>and</strong> numerical methods. We found that when the effectsof radiation reaction on the electron motion are significant, the difference between QED<strong>and</strong> classical results are also large.44

Simulation study of self-injection <strong>and</strong> density-ramping-injection inLWFA based on typical 100 TW laser facilities by OOPICLI Dazhang 1 GAO Jie 2 ZhU Xiongwei 3 HE An 41 Institute of High Energy Physics, Chinese Academy of ScienceOne of the most important advanced acceleration concepts is laser plasma acceleration.<strong>The</strong> amplitude of the accelerating electric fields generated from Laser WakeFieldAccelerators (LWFA) may beyond 100 GV/m, which is more than 1000 times higher thantraditional radio frequency accelerating structures. We do 2-D simulations based ontypical 100TW laser facilities by OOPIC. At first, we fix the laser parameters <strong>and</strong> doexplicit plasma density scanning to find a matched plasma density as in a real LWFAexperiment. And then in order to solve the problems during self-injection, we givetheoretical <strong>and</strong> simulation results of density-ramping-injection (DRI) methods. It is shownthat the number of captured electrons is 10 times larger in DRI than in normalself-injection process <strong>and</strong> the energy <strong>and</strong> absolute energy spread of the bunch doesn’tchange a lot.Funding supported by NSFC (10525525, 10775154) <strong>and</strong> Knowledge Innovation Funds ofIHEP, CAS (H75452A0U2).45

Vacuum laser-driven electron acceleration by Airy beamsJian-Xing Li 1 , Wei-Ping Zang 1, 2 , Jian-Guo Tian 1, 21Photonics Center, <strong>School</strong> of Physics, Nankai University, Tianjin 300071, China2<strong>The</strong> Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda AppliedPhysics <strong>School</strong>, Nankai University, Tianjin 3000457, ChinaDue to the invention of the chirped pulse amplification (CPA) technique, laser accelerationin vacuum has been an active research area in recent years. Laser-driven electronacceleration relies on the large laser intensity that can be achieved by focusing laserbeams down to spot sizes in the order of wavelength. However, a shortcoming of many ofthese schemes is that the interaction length over which the high intensity can be sustainedis relatively short due to transverse spreading (diffraction). <strong>The</strong>refore, electronacceleration by quasi-diffraction-free beams, Bessel beam, has attracted widespreadattentions.Another known diffraction-free beam is Airy wave packets, first predicted by Berry <strong>and</strong>Balazs within the context of quantum mechanics. This intriguing class of beams was onlyrecently predicted <strong>and</strong> realized in optical domain. Its key features are transverselyaccelerating <strong>and</strong> diffraction-free during propagation. Unlike other-diffracting beams, theAiry beam does not result from conical superposition, is possible even in one-dimension,<strong>and</strong> is highly asymmetric. Airy beams have been used in optical micromanipulation. In thisposter we present the first use of the Airy beam in vacuum electron acceleration. <strong>The</strong>characteristics of acceleration <strong>and</strong> non-diffraction of Airy beam in one dimensionalconfiguration lead to the formation of a long “asymmetric field channel” (AFC) along thepropagation axis. Electron senses a continual acceleration phase in AFC, so 1D Airybeam is more appreciable to the accelerating of electron than other diffraction <strong>and</strong>diffraction-free beams. Moreover, the injection energy of electron plays an important rolein determining the final energy gain. An initial fast electron can be captured by AFC, <strong>and</strong> aslow electron could be captured or reflected.Funding supported by the Natural Science Foundation of China (grant 60678025), ChineseNational Key Basic Research Special Fund (2006CB921703), Program for New CenturyExcellent Talents in University, <strong>and</strong> 111 Project (B07013).46

Ion jet generation in the ultra-intense laser interactions withrear-side concave targetBin Liu 1,2 Hua Zhang 1,3 Li-Bin Fu 1,3 Yu-Qiu Gu 4 Bao-Han Zhang 4 Ming-Ping Liu 5Bai-Song Xie 6 Jie Liu 1,3 Xian-Tu He 1,31 Center for Applied Physics <strong>and</strong> Technology, Peking University, Beijing, 100084, China2 Graduate <strong>School</strong>, China Academy of Engineering Physics, Beijing 100088, China3 Institute of Applied Physics <strong>and</strong> Computational Mathematics, Beijing, 100088, China4 Fusion Research Center, Chinese Academy of Engineering Physics, Mianyang, China5 <strong>School</strong> of Information Engineering, Nanchang University, Nanchang, China6 College of Nuclear Science <strong>and</strong> technology, Beijing Normal University, Beijing 100875, China<strong>The</strong> ion jet generation from the interaction of an ultraintense laser pulse <strong>and</strong> a rear-sideconcave target is investigated analytically using a simple fluid model. We find that the ionexp<strong>and</strong>ing surface at the rear-side is distorted due to a strong charge-separation field, <strong>and</strong>that this distortion becomes dramatic with a singular cusp shown on the central axis at acritical time. <strong>The</strong> variation of the transverse ion velocity <strong>and</strong> the relative ion densitydiverge on the cusp, signaling the emergence of an on-axis ion jet. We have obtainedanalytical expressions for the critical time <strong>and</strong> the maximum velocity of the ion jet, <strong>and</strong>suggested an optimum shape for generating a collimated energetic ion jet. <strong>The</strong> abovetheoretical analysis has been verified by particle-in-cell (PIC) numerical simulations.Funding supported by the National Fundamental Research Programme of China (ContactNos.2007CB815103,2007CB814800), the National Natural Science Foundation of China(Contact Nos. 10725521, 10875015, 10834008), <strong>and</strong> the Foundation of CAEP (Contact No.2006Z0202).47

Generation of low density plasma channels <strong>and</strong> optical guiding inplasma waveguidesMingwei Liu 1,2 , Aihua Deng 1 , Jiancai Xu 1 , Changquan Xia 1 , Cheng Wang 1 , Jiansheng Liu 1 ,Baifei Shen 1, Ruxin Li 1, Zhizhan Xu 11 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics <strong>and</strong> FineMechanics, Chinese Academy of Sciences, Shanghai 201800, China2 <strong>School</strong> of Physics, Hunan University of Science <strong>and</strong> Technology, Xiangtan Hunan, 411201,ChinaA technique is developed to trigger ablative capillary discharges transversely by a laserpulse. This transverse laser ignition method has several advantages over previoustechniques employing a laser pulse collinear with the capillary, including increasedcapillary lifetime <strong>and</strong> simpler arrangement of the igniting <strong>and</strong> the driving pulses forlaser-wakefield acceleration. Using this technique long plasma channels (waveguides) areproduced with low jitter. An off-axis incident model is presented to analyze the influence ofbeam pointing fluctuation on the propagation properties of intense laser beams in suchkinds of waveguides. Optical guiding of a 200TW laser pulse over 3-cm in plasmawaveguides is also demonstrated in experiments.Funding supported by the National Natural Science Foundation (Grant Nos.10734080 <strong>and</strong>10834008), the National Basic Research Program of China (Grant No. 2006CB806000), theChinese Academy of Sciences, the Shanghai Commission of Science <strong>and</strong> Technology (GrantNos. 06DZ22015 <strong>and</strong> 0652nm005), <strong>and</strong> the Hunan Provincial Natural Science Foundation ofChina (Grant No. 09JJ3012).48

Interaction of ultraintense <strong>and</strong> ultrashort laser pulse with overdenseplasma targetShixia Luan Wei YuShanghai Institute of Optics <strong>and</strong> Fine Mechanics, Chinese Academy of Sciences, 201800,Shanghai, ChinaA simple but comprehensive 2-dimensional analytical model for laser <strong>and</strong> overdenseplasma interaction during the normal incidence by a ultrashort <strong>and</strong> ultraintense Gaussianlaser pulse with a finite spot size on a solid-density plasma is proposed. Hole punching bythe laser pulse is a key feature in this process, which induces strong spatial chargeseparation <strong>and</strong> plays an crucial role for the occurrence of linear mode conversion (both forcircularly <strong>and</strong> linearly polarized laser pulse) <strong>and</strong> J× B heating (only for linearly polarizedlaser pulse). It is also found that the depth of the hole increases with higher laser intensity49

High charged electrons generation by dual laser pulses 1Meng Wen 1 ,2 ,3 Baifei Shen 21 Shanghai Institute of Optics <strong>and</strong> Fine Mechanics, Chinese Academy of Sciences, Shanghai,China2 IHIP, Peking University, Beijing China3 Institute of Photonics & Photon-Technology, North-West University, Xi’an ChinaLarge amount of energetic electrons generated in laser wake fields driven by dual parallellaser pulses is investigated with three-dimensional (3D) PIC simulation. By adjusting thedistance between the pulses, bubbles with different structure are formed, which results indifferent injection efficiency. Compared with the single pulse case, the charge of theenergetic electrons can be doubled when the distance between two pulses is largeenough. A characteristic distance between the pulses is obtained, above which the totalamount of the energetic electrons increases linearly by applying more laser pulses. <strong>The</strong>reis no limit for the charge increase in our scheme, as long as the plasma is wide enough sothat more pulses can be applied.Funding supported by the National Natural Science Foundation of China (Project 60921004<strong>and</strong> 10834008), the Program of Shanghai Subject Chief Scientist (09XD1404300), ShanghaiNatural Science Foundation (10ZR1433800) <strong>and</strong> the 973 program (No. 2006CB806004)50

Numerical research on evaporation of target bombarded by pulsedion beamWu Di 1 Gong Ye 2 Liu Jin-Yuan 2 Wang Xiao-Gang 2 Liu Yue 2 Ma Teng-Cai 21 Collge of Physical Science <strong>and</strong> Technology, Dalian University, Dalian 116622, China2 Key Laboratory of Materials Modification by Laser, Ion <strong>and</strong> Electron Beams, DalianUniversity of Technology, Dalian 116024, ChinaTo discuss the mechanism of plasma transport in vacuum, the ejection model ofhydrodynamic equations related to the ablation shape of the target has been establishedby using the ablation results as initial conditions of plasma formed by high intensity pulsedion beam irradiation. <strong>The</strong> spatial <strong>and</strong> temporal evolution profiles of plasma pressure, massdensity <strong>and</strong> velocity are calculated. <strong>The</strong> plasma transport is faster based on our modelthan vertical one, <strong>and</strong> the formation of film relates to the distance between target <strong>and</strong>substrate can be well explained according to our ejection model.Funding supported by the National Natural Science Foundation of China (Grant No.10975026).51

Generation of tens of GeV quasi-monoenergetic proton beamsfrom a moving double layer formed by ultraintense lasers atintensity 10 21 –10 23 W cm −2Lu-Le Yu 1 , Han Xu 2 , Wei-Min Wang 1 , Zheng-Ming Sheng 1,3,5 , Bai-Fei Shen 4 , Wei Yu 4 <strong>and</strong> JieZhang 1,31 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS, Beijing100190, People’s Republic of China2 <strong>School</strong> of Computer Science, National University of Defence Technology, Changsha 410073,Weimin Wang China3Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China4 Shanghai Institute of Optics <strong>and</strong> Fine Mechanics, CAS, Shanghai 201800, ChinaWe present a scheme for proton acceleration from a moving double layer formed by anultraintense circularly polarized laser pulse with intensity10 21 –10 23 Wcm −2 irradiated on acombination target. <strong>The</strong> target is composed of a thin overdense proton-rich foil located atthe front followed by an underdense gas region behind with an effective Z/A ratio of theorder of 1/3. When the areal density of the thin foil is small enough, the protons togetherwith electrons in the thin overdense foil can be pre-accelerated under the laser irradiation.As the laser pulse passes through the thin foil <strong>and</strong> propagates in the underdense gasregion, it excites high-amplitude electrostatic fields moving at a high speed, which appearlike a moving double layer. <strong>The</strong> pre-accelerated protons can get trapped <strong>and</strong> acceleratedin the moving double layer <strong>and</strong> tens of GeV quasi-monoenergetic proton beams areachieved, provided the laser intensity <strong>and</strong> plasma density are properly chosen, asdemonstrated by one-dimensional (1D) <strong>and</strong> 2D particlein-cell (PIC) simulations.Funding supported by NSFC (grant numbers 10935002, 10734130 <strong>and</strong> 60621063),theNational High-Tech ICF Committee of China <strong>and</strong> the National Basic Research Program ofChina (grant numbers 2007CB815101 <strong>and</strong> 2007CB815105).52

Ultra-intense single attosecond pulse generated fromcircularly-polarized laser interacting with overdense plasmaLiangliang Ji, Baifei Shen, Xiaomei Zhang, Meng Wen, Changquan Xia, Wenpeng Wang,Jiancai Xu, <strong>and</strong> Yahong YuState Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics <strong>and</strong> FineMechanics, Chinese Academy of Sciences, Shanghai 201800, ChinaUltra-intense high order harmonics <strong>and</strong> furthermore attosecond pulses can be generatedby relativistic linearly polarized laser pulse interacting with overdense target, which haspreviously been demonstrated theoretically <strong>and</strong> experimentally. However, with linearlypolarized lasers, there would be a train of attosecond pulses which is difficult forapplications. By particle-in-cell simulations <strong>and</strong> analysis, we propose that employing acircularly polarized pulse a single attosecond pulse is generated by itself <strong>and</strong> nopost-treatments are required. This method is much more convenient than previousproposals to isolate pulse from the pulse train by linearly polarized lasers. We give theanalytical mode <strong>and</strong> it describes the simulation results very well. Parameter relationshipshows that using a single-cycle21 210 W/cm circularly polarized laser, a single 36asattosecond pulse with peak intensity of21 26.3× 10 W/cm is generated. Two dimensionalsimulation shows that the proposal is also efficient in multi-dimension geometries.53

Self-generated magnetic fields in the relativistic laser-plasmainteractionA. AbudurexitiPhysics Department, Xinjiang University, Urumqi , 830046Strong magnetic fields can be generated when an intense laser pulse interacts withplasma. <strong>The</strong> spontaneous magnetic fields as large as several mega-Gauss have beendirectly measured in the blowoff plasma in front <strong>and</strong> rear of solid targets ,<strong>and</strong> attributed toa mechanism that occurs when the plasma density gradient ∇ n <strong>and</strong> temperature gradient∇ T are not collinear, <strong>The</strong>se magnetic fields, which can become strong enough tosignificantly affect transport, are attributed to nonlocal effects that are missing in thest<strong>and</strong>ard, local theories .In this paper ,<strong>The</strong> self-generated magnetic field by a relativisticlaser pulse irradiated on a thin plasma target at the perpendicular incidence isinvestigated using a two dimensional particle-in cell simulation.54

High resolution emittance <strong>and</strong> energy spread measurements of80- 135 MeV electron beams from a laser driven plasma wakefieldaccelerator on the ALPHA-X beam lineG. Manahan E. Brunetti R. P. Shanks M. P. Anania S. Cipiccia R. T. L. Burgess R.Issac M. R. Islam B. Ersfeld G. H. Welsh S. M. Wiggins <strong>and</strong> D. A. JaroszynskiDepartment of Physics, University of Strathclyde, Glasgow, G4 0NG, UK<strong>The</strong> normalised transverse emittance characterises the quality of an electron beamgenerated from the laser-plasma wakefield accelerator (LWFA). Brightness, parallelism<strong>and</strong> focusability are all functions of the emittance. Here, we present a high-resolutionsingle shot method of measuring the transverse emittance of a 125 MeV electron beamgenerated from a LWFA using a pepper-pot mask. An average normalised emittance ofaround 1 mm mrad was measured, which is comparable to that of a conventionalaccelerator. We also show high resolution measurements of the energy spreaddetermined using a magnetic dipole spectrometer.Funding supported by U.K. EPSRC <strong>and</strong> the Scottish Universities Physics Alliance.55

Ultrafast pulse-train laser leading to desktop intense THzfree-electron laserYen-Chieh Huang a , Kuei-Feng Hong a , Yen-Yin Lin a , An-Chung Chiang b , Chiahsian Chen aaDepartment of Electrical Engineering, b Nuclear Science <strong>and</strong> Technology DevelopmentCenter, National Tsinghua University, Hsinchu 30013, TaiwanWe report the development of a high-power THz pulse train laser to drive an electronphotoinjector, which in turn drives a single-pass free electron laser to generate fullytunable, coherent, intense THz radiation in a desktop dimension. In this work, weengineer a TW-power, THz pulse train laser <strong>and</strong> further encode the laser pulse structureto an electron beam through a photocathode electron accelerator. Such an electron beam,carrying the coherence of the laser, is ideal for generating high-brightness electronradiation at frequencies that can not be reached by a solid-state laser.This work is supported by National Tsinghua University under project code 98N2534E1 <strong>and</strong> byNational Science Council under Contract NSC 99-2112-M-007 -013 -MY3.56