Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
Electromagnetic Design of an RFQ for the Front End Test Stand at RAL
The goal of the RAL front end test stand is
to demonstrate cleanly chopped bunches of
a 60mA H − ion beam at 3MeV. The acceleration
of the H − ions from 65KeV to 3MeV will
A. Kurup (Imperial College of Science and Technology, Department
of Physics) A.P. Letchford (CCLRC/RAL/ISIS)
be done using a radio frequency quadrupole (rfq) operating at a resonant frequency of 324MHz. The two types of rfq
considered were a 4-vane and a 4-rod. The 4-vane has a higher Q-value but the post-production tuning is limited. The
4-rod design is easier to manufacture but requires complicated cooling at 324MHz. The results of electromagnetic
simulations using CST Microwave Studio are presented for the 4-vane type and 4-rod type rfq.
Mechanical Design and RF Measurement on RFQ for Front-end Test Stand (FETS) at RAL
The mechanical designs and RF measurement
results will be presented of both the
cold model of a 324MHz 4-vane and 4-rod
RFQ. These models are part of the development
of the Proton Driver Front End Test
P. Savage, Y.A. Cheng (Imperial College of Science and Technology,
Department of Physics) A.P. Letchford (CCLRC/RAL/ISIS)
J.K. Pozimski (CCLRC/RAL)
Stand at the Rutherford Appleton Laboratory (RAL) in the UK. The design concepts will be shown as well as the
manufactured cold models. Some issues in manufacturing of the RFQs will be pointed out, and specific modifications
will be explained. Results of thermal simulations and calculations will be presented as well as measurements of the
resonant frequency and Q-value.
Wideband Low-output-impedance RF System for the Second Harmonic Cavity in the ISIS
Synchrotron
Wideband low-output-impedance RF system
for the second harmonic cavity in the ISIS
synchrotron has been developed by the collaboration
between Argonne National Laboratory,
US, KEK, Japan and Rutherford Appleton
Laboratory, UK. Low output impedance
is realized by the feedback from plate
Y. Irie (JAEA/J-PARC) D. Bayley, G.M. Cross, I.S.K. Gardner, M.G.
Glover, D. Jenkins, A. Morris, A. Seville, S.P. Stoneham, J.W.G.
Thomason, T. Western (CCLRC/RAL/ISIS) J.C. Dooling, D. Horan,
R. Kustom, M.E. Middendorf, G. Pile (ANL) S. Fukumoto, M.
Muto, T. Oki, A. Takagi, S. Takano (KEK)
output to grid input of the final triode amplifier, resulting in less than 30 ohms over the frequency range of 2.7 - 6.2
MHz which is required for the second harmonic cavity. The vacuum tubes in the driver and final stages are both
operated in class A, and a grid bias switching system is used on each tube to avoid unnecessary plate dissipations
during a non-acceleration cycle. High power test was performed with a ferrite-loaded second harmonic cavity, where
the bias current was swept at 50 Hz repetition rate. The maximum voltage of 12kV peak per accelerating gap was obtained
stably at earlier period of an acceleration cycle. A beam test with this system is planned at the ISIS synchrotron
in order to investigate how the low impedance system works under heavy beam loading conditions, and is capable of
mitigating the space charge detuning at the RF trapping stage.
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MOPCH116
MOPCH117
MOPCH118