Abstracts Brochure - CERN

MOPCH113
MOPCH114
MOPCH115
26-Jun-06 16:00 - 18:00 MOPCH — Poster Session
Re-bunching RF Cavities and Hybrid Quadrupoles for the RAL Front-end Test Stand
(FETS)
The proposed FETS project at RAL will test a
D.C. Plostinar, M.A. Clarke-Gayther (CCLRC/RAL/ASTeC) fast beam chopper in a 3.0 MeV H − Medium
Energy Beam Transport (MEBT) line. Space
restrictions in the MEBT line place constraints on component length and drive the requirement to identify compact
component configurations. A description is given of candidate re-bunching RF cavity and hybrid quadrupole designs.
The cavity options considered are the space efficient DTL shaped cavity with integrated quadrupoles, and the high
shunt impedance CCL shaped cavity. The advantages and the disadvantages of both structures are discussed and
a modified cavity geometry with integrated quadrupoles and a high shunt impedance is presented. The compact
hybrid quadrupole configurations considered are the ’tandem’ combination of permanent magnet (PMQ) and Electromagnetic
(EMQ) types, and the concentric combination of PMQ and laminar conductor (Lambertson) EMQ types.
Progress on Dual Harmonic Acceleration on the ISIS Synchrotron
A. Seville, D.J. Adams, C.W. Appelbee, D. Bayley, N.E. Farthing,
I.S.K. Gardner, M.G. Glover, A. Morris, B.G. Pine, J.W.G. Thomason,
C.M. Warsop (CCLRC/RAL/ISIS)
80
The ISIS facility at the Rutherford Appleton
Laboratory in the UK is currently the most intense
pulsed, spallation, neutron source. The
accelerator consists of a 70 MeV H − Linac
and an 800 MeV, 50 Hz, rapid cycling, proton
Synchrotron. The synchrotron beam intensity is 2.5·10 13 protons per pulse, corresponding to a mean current of
200 µA. The synchrotron beam is accelerated using six, ferrite loaded, RF cavities with harmonic number 2. Four
additional, harmonic number 4, cavities have been installed to increase the beam bunching factor with the potential
of raising the operating current to 300 µA. As ISIS has a busy user schedule the time available for dual harmonic
work has been limited. However, much progress has been made in the last year and encouraging results have been
obtained. This paper reports on the hardware commissioning and beam tests with dual harmonic acceleration.
Transverse Space Charge Studies for the ISIS Synchrotron
The ISIS Facility at the Rutherford Appleton
C.M. Warsop (CCLRC/RAL/ISIS)
Laboratory in the UK produces intense neutron
and muon beams for condensed matter
research. It is based on a 50 Hz proton synchrotron which, once the commissioning of a new dual harmonic RF system
is complete, will accelerate about 3.5·10 13 protons per pulse from 70 to 800 MeV, corresponding to mean beam powers
of 0.2 MW. Following this upgrade, transverse space charge is expected to be one of the main intensity limitations,
and is also a key factor for further machine upgrades. A programme of R&D on transverse space charge is now
under way, aiming not only to improve the ISIS ring but also to exploit it as an experimental tool for testing theory
and codes. This paper summarises work so far, outlining calculations for coherent envelope modes on ISIS, using
numerical solutions of the envelope equation to show the expected behaviour near half integer resonance. Progress
on work linking these predictions with more realistic beam models in space charge codes, and extending calculations
to images, coupling and non linear resonances will be described. Plans and preparations for experiments, along with
initial results, will also be presented.