Session 8: Low and Intermediate Energy Accelerators and ... - CERN

with main beam into the SPring-8 storage ring and then
spoil the purity of the stored beam. The dark currents
are mainly composed of a grid emission current from a
thermionic gun and field emission currents from rf
accelerating structures. A beam deflector for kicking
only the grid emission by a pulsed electric field was
developed and installed in the SPring-8 linac. We
observed that the beam deflector greatly reduced the
grid emission current accelerated up to 1 GeV. The
measured purity of the stored single-bunched beam was
about 5x10^-6 when the deflector operated, which was
almost 1/100 of the purity without filtering by the
deflector. However, the deflector, which is installed
before the prebucher, cannot reduced the field emission
currents from the buncher cavities and the first
acccelerating structure. These dark currents take
considerable proportion of the total dark currents
observed at the end of the linac. We are trying to spin
off the field emission currents by weak magnetic fields
across the accelerating structure generated by several
coils.
Type of presentation requested: Poster
Classification: [A08] Linear Accelerators
74-1547 - First Commissioning Experiments at
DARHT-II
Carl Ekdahl (LANL, Los Alamos, New Mexico)
The second axis of the Dual Axis Radiographic Hydro-
Test (DARHT) facility will provide up to four short(<
150 ns) radiation pulses for flash radiography of highexplosive
driven implosion experiments[1]. The
DARHT-II linear induction accelerator (LIA) will
produce a 2-kA,18-MeV,2-micro-s electron beam. A
fast kicker will cleave four short pulses out of the
beam, which will focused onto a tantalum target for
conversion to bremsstrahlung pulses for radiography.
The first tests of the second axis accelerator were
designed to demonstrate the technology, and to meet
the modest performance requirements for closing out
the DARHT-II construction project. These experiments
demonstrated that we could indeed produce a 1.2 kA
beam with pulse length 0.5-1.2 &#61549;s and
accelerate it to 12.5 MeV. These de-rated parameters
were chosen to minimize risk of damage in these first
experiments with this novel accelerator. The beam was
stable to the BBU instability for these parameters. In
fact, we had to reduce the magnetic guide field by a
factor of 5 before any evidence of BBU was observed.
We will discuss the results of these experiments and
their implications, as well as our plans for continuing
with DARHT-II commissioning.
United States Department of Energy
Type of presentation requested: Poster
Classification: [A08] Linear Accelerators
75-165 - New Developments of a Laser Ion Source for
Ion Synchrotrons
Sergei Kondrashev, Alexander Balabaev, Konstantin
Konukov, Boris Sharkov, Alexander Shumshurov (ITEP,
Moscow), Olivier Camut, James Chamings, Hartmut
Kugler, Richard Scrivens (CERN, Geneva), Andrei
Charushin, Konstantin Makarov, Yuri Satov, Yuri
Smakovskii (SRC RF TRINITI, Moscow region)
Laser Ion Sources (LIS) are well suited to filling
synchrotron rings with highly charged ions of almost any
element in a single turn injection mode. We report the first
measurements of the LIS output parameters for Pb27+ ions
generated by the new 100 J/1 Hz Master Oscillator - Power
Amplifier CO2-laser system. A new LIS has been designed,
built and tested at CERN, as an ion source for ITEP-TWAC
accelerator/accumulator facility, and as a possible future
source for an upgrade of the Large Hadron Collider (LHC)
injector chain. The use of the LIS based on 100 J/1 Hz CO2laser
together with the new ion LINAC, as injector for
ITEP-TWAC project is discussed.
Type of presentation requested: Poster
Classification: [T01] Proton and Ion Sources
76-263 - Improved Electron Cyclotron Resonance Ion/
Plasma Device Using Novel Cusp Mirror Magnetic Field
Md Haroon Rashid, Rakesh Bhandari, Chaturanan Mallik
(DAE/VECC, Calcutta)
Sufficient beams of the Highly Charged Heavy Ion (HCHI)
have been obtained using some techniques in conventional
electron cyclotron resonance ion sources (ECRIS) but at the
cost of simplicity and economy. Many workers identified
that the cusp magnetic field (CMF) was the best as it has
more confining feature but a little current of HCHIs
extracted practically. The CMF has been reconfigured
adopting a simple, novel and cost-effective novel technique.
It uses a pair of concentric coils either normal-conducting or
super-conducting and a highly permeable mid-iron disk for
the field due to coil system or available permanent magnet
having very high remanence and coercivity. It can be
designed now for higher microwave frequencies for high-B
mode operation of the cusp ECRIS. The novel CMF at the
cusp positions is referred to a theory of equilibrium, which
takes into account mirror reflection of particles. A system of
two ion-sources used for RIB production may not be
required now. It can be designed without having any
permanent magnet either. Now it is possible to place a cusp
ECRIS near the thick target for ionizing the effusing out
radioactive fragments to high charge-state. A simple design
of 14.4 GHz cusp mirror ECRIS and a scheme of obtaining
highly charged RIB will be finally discussed. This technique
can herald a new epoch for development of ECR ion/
plasma device for many advantageous applications.
Type of presentation requested: Poster
Classification: [T01] Proton and Ion Sources