Abstracts Brochure - CERN

MOPCH057
MOPCH058
MOPCH059
26-Jun-06 16:00 - 18:00 MOPCH — Poster Session
A Design of 1.8 keV Compton X-ray Generator for the KAERI SC RF LINAC
A.V. Bondarenko, S.V. Miginsky (BINP SB RAS) Y.H. Han, Y.U.
Jeong, B.C. Lee, S. H. Park (KAERI)
62
A quasi-monochromatic X-ray source based
on the KAERI SC linac system has been designed
and is being manufactured now. A 10
MeV 10 mA electron beam together with a 20
W 1.06 ?m laser beam will be used for 1.8 keV Compton X-ray generation with a few percentage of energy spread and
107 photons per second. A simple straight beamline was designed to deliver the electron beam with no degradation
of its emittance and energy spread and to focus it to a proper size to produce the desired X-rays. We expect the first
demonstration of 1.8 keV Compton X-ray generation in autumn 2006.
RF Photogun as Ultra Bright Terahertz Source
W.P.E.M. Op ’t Root, M.J. Loos, O.J. Luiten, M.J. Van der Wiel, T.
van Oudheusden, S.B. van der Geer (TUE)
Recently research into new terahertz (0.3 to
30 THz) light sources has gained a lot of interest.
Especially compact sources capable of
delivering high peak fields (∼ 1 MV/cm), in
a short pulse. To achieve this, we will use short relativistic electron bunches, created by photoemission and accelerated
in an rf-photogun, to create THz light by means of coherent transition radiation. Because wavelengths smaller and
comparable to the bunch length add up coherently, the intensity scales with N 2 , with N the number of electrons in
the bunch. In the first experiments we expect to create THz light pulses with a bandwidth of 1 THz and 1 µJ per
pulse. If such a light pulse is focused on a spot of radius 250 µm, this corresponds to peak electrical fields of 1 MV/
cm. The eventual goal is to increase the bandwidth of the source, by creating shorter electron bunches. This will be
accomplished by choosing a suitable radial laser profile, leading to ellipsoidal electron bunches, which can be focused
and compressed very effectively. Eventually this will lead to THz pulses with a bandwidth of 10 THz and energy of
100 µJ. This corresponds to peak electrical fields of 10 MV/cm and higher.
From Pancake to Waterbag: Creation of High-brightness Electron Bunches
T. van Oudheusden, O.J. Luiten, W.P.E.M. Op ’t Root, M.J. Van der
Wiel, S.B. van der Geer (TUE)
Our recent insight is that, when creating
high-brightness electron bunches, the major
problem is not space charge density itself,
but its distribution. Non-linear space charge
effects lead to a decrease of brightness. We have a novel recipe of creating waterbag bunches (uniformly charged
3D ellipsoids), which have linear space charge fields. Because of these linear fields we have control of the Coulomb
explosion of the bunches. Furthermore, using linear charged particle optics, waterbags can be compressed and focussed
with conservation of brightness. Our recent simulations prove that it is possible to create such ideal waterbag
bunches in practice. The recipe is to create at the cathode a pancake-like electron bunch with a "hemisphere" charge
density distribution. During acceleration this pancake will evolve into a waterbag by its own space charge forces, if
two conditions on the acceleration field and the surface charge density are fulfilled. These two conditions are leading
to a parameter space, which is explored by simulations. We will present numerical simulations and the present status
of the experimental realization.