Abstracts Brochure - CERN

WEPLS121
WEPLS122
WEPLS123
28-Jun-06 16:00 - 18:00 WEPLS — Poster Session
Power Systems Upgrades on the ISIS Synchrotron: a Progress Report
ISIS, situated at the Rutherford Appleton
S. West, M.G. Glover, J.W. Gray, A.J. Kimber (CCLRC/RAL/ISIS) Laboratory (RAL) is the world’s most powerful
pulsed neutron source. Intense pulses
of neutrons are produced every 20 mS when an 800 MeV proton beam is directed into a heavy metal target by a
synchrotron. On the ISIS synchrotron the main magnets are arranged in a resonant "White Circuit"* connected in
series with capacitor banks and tuned to 50 Hz. This method allows the magnets to be fed with superimposed AC and
DC currents. ISIS is shortly to be upgraded by the addition of a second target station with a new suite of instruments
requiring a higher beam current but the synchrotron will remain at the heart of the facility. The AC supply to the
White circuit consists of a motor-alternator set that feeds power into the circuit via a ten-winding choke weighing
approximately 120 tons. These components are aging (dating in part to the 1960’s) and projects are in hand to replace
them with new systems that will increase reliability, performance and some immunity to variations in the incoming
mains electricity supply. This paper discusses progress so far and issues that have emerged during installation and
testing.
*M. G. White et al. “A 3-BeV High Intensity Proton Synchrotron”, The Princeton-Pennsylvania Accelerator, CERN
Symp.1956 Proc., p525.
Multiphase Resonant Power Converter for High Energy Physics Applications
Accelerators used for experiments in high-
M.J. Bland, J. Clare, P. W. Wheeler (University of Nottingham) energy physics require very high power radio
frequency sources to provide the energy
needed to accelerate the particles. The RF power needs to be stable and predictable such that any variation in the
supplied RF power has a limited and acceptable impact on the accelerated beam quality. This paper considers the
design of a "long-pulse" modulator supply rated at 25kV, 10A (250kW peak power, duty ratio 10%, 25kW average
power, pulse length ∼ 1 – 2ms). The supply is based on direct modulation of a multi-phase resonant power supply,
fed by an active rectifier. The objectives of the development are to produce a compact power supply, with low stored
energy and with high power quality at the utility supply. The paper provides a brief overview of the technology,
followed by a discussion of the design choices. Initial results from the laboratory prototype will be included.
Initial Experimental Results of a New Direct Converter for High Energy Physics Applications
D. Cook, J. Clare, P. W. Wheeler (University of Nottingham) C.
Oates (Areva T&D) J.S. Przybyla, R. Richardson (e2v Technologies)
368
This paper presents practical results for a
new type of power supply for high energy
physics CW applications. The converter is
a direct topology operating with a high fre-
quency (resonant) link. Losses are minimised by switching at zero current. High operating frequency reduces the
filter and transformer size. The transformer uses the latest nano-crystalline materials to further reduce losses. Where
possible, circuit elements are incorporated into the transformer to reduce the physical size of the converter. Design of
this transformer to accommodate the insulation, VA rating and circuit elements is non-trivial. The Radio Frequency
power generated is stable and predictable, whilst the reduced energy storage in filter components removes the need
for crowbar circuits. Potential benefits of this converter when compared to conventional approaches are discussed.