Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
Operation of a Helium Cryogenic System for a Superconducting Cavity in an Electron
Storage Ring
A 500 MHz superconducting cavity maintaining
the energy of electrons in the storage F. Z. Hsiao, S.-H. Chang, W.-S. Chiou, H.C. Li (NSRRC)
ring of TLS light source started from the year
2005. A helium system dedicated to keep the niobium cavity at 4.5 K has begun its operation since the year 2003.
The cryogenic system provides maximum refrigeration of 469 W or liquefaction rate of 134 l/hr. The constraint from
the superconducting cavity leads to specific features of the cryogenic system. This paper presents the operation of
the cryogenic system as the superconducting cavity at different conditions. The interaction in between the cryogenic
system and the superconducting cavity and the constraints on the starting and shutdown of the cryogenic system are
indicated.
SNS 2.1K Cold Box Turn-down Studies
The Spallation Neutron Source (SNS) at Oak
Ridge National Laboratory is nearing completion.
The cold section of the Linac consists
of 81 superconducting radio frequency
F. Casagrande, P.A. Gurd, D.R. Hatfield, M.P. Howell, W.H. Strong
(ORNL) D. Arenius, V. Ganni (Jefferson Lab)
cavities cooled to 2.1K by a 2400 watt cryogenic refrigeration system. The 2.1K cold box consists of four stages of
centrifugal compressors with LN2-cooled variable speed electric motors and magnetic bearings. The cryogenic system
successfully supported the Linac beam commissioning at both 4.2K and 2.1K and has been fully operational since
June 2005. This paper describes the control principles utilized and the experimental results obtained for the SNS cold
compressors turn-down capability to about 30% of the design flow, and possible limitation of the frequency dependent
power factor of the cold compressor electric motors, which was measured for the first time during commissioning.
These results helped to support the operation of the Linac over a very broad and stable cold compressor operating
flow range (refrigeration capacity) and pressure. This in turn helped to optimise the cryogenic system operating
parameters, minimizing the utilities and improving the system reliability and availability.
Studies of the Alignment Tolerance in the Injector System of the IFUSP Microtron
The Instituto de Fmsica da Universidade de
Sco Paulo (IFUSP) is building a two-stage 38 T.F. Silva, A.A. Malafronte, M.N. Martins, P.B. Rios (USP/LAL)
MeV continuous-wave racetrack microtron.
In this work, we describe the determination of alignment tolerances for the injector system of the IFUSP Microtron.
This system consists of a linear accelerator with input energy of 100 keV and output energy of 1.8 MeV. The work
presented ere involves analysis of our possibilities of alignment, the beam specifications for the acceleration structures
and the strength of the correcting coils. Simulations were made using a method based on rotation matrices that allows
for misalignments in the optical elements. It uses a tolerance parameter, given by the user, which is interpreted as a
standard deviation of the normal misalignment distribution used to shuffle a configuration. A 5% loss of particles is
achieved at a tolerance of 0.25-mm, without the inclusion of correcting coils (steerings) in the simulations.
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