Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
Peak Field Optimization for the Superconducting CH Structure
The Cross-Bar H-type (CH) cavity is a multigap
drift tube structure operated in the H- H. Liebermann, H. Podlech, U. Ratzinger (IAP)
210 mode which has been developed at the
IAP Frankfurt and in collaboration with GSI. Based on detailed numerical simulations a 19 cell prototype cavity from
massive Nb was realised. For optimization of the magnetic and electric peak fields, detailed numerical simulations
with CST MicroWave Studio have been performed. After successful experiments on the superconducting prototype
cavity calculations about improved drift tube geometries with respect to field emission took place. Additionally, the
stem geometry was further improved by simulations.
Dry-ice Cleaning on SRF Cavities
High pressure rinsing with ultra-pure water
is the well-proven standard cleaning step af- A. Brinkmann, J.I. Iversen, D. Reschke, J. Ziegler (DESY)
ter chemical or electrochemical surface treatment
of SRF cavities. Dry-ice cleaning (DIC) is a powerful additional cleaning option which depends on the sublimation-impulse
method. Particles and film contaminations, especially hydro-carbons, are removed without residues.
Furthermore DIC offers the possibility of a final horizontal cleaning of a fully equipped cavity because water is not
present in the cleaning process. Horizontal cleaning tests on single-cell cavities showed promising high gradient,
high Q-value performances, but field emission is still the limiting effect. On the basis of these tests a new IR-heater
module is installed to keep a high temperature gradient between the CO2 jet and the cavity surface. New test results
for this optimized cleaning set-up will be presented.
Performance Limitations of TTF Cavities in Accelerator Operation and their Relation to
the Assembly Process
Several accelerator modules with superconducting
cavities have been assembled for L. Lilje (DESY)
TTF. The paper reviews the performance of
these structures and will try to correlate their performance to information about the assembly process. In some cases
a performace degradation could be attributed to problems in this process. The introduction of additional quality
control steps improved accelerator module performance. For example, the more recently assembled modules have
shown the expected acceleration gradients and no vacuum leaks.
Structural Analysis for a Half-reentrant Superconducting Cavity
A half-reentrant cavity (1300 MHz, beta=1.0)
is being developed at Michigan State University
for use in a superconducting linear
collider and other applications. The electro-
E. Zaplatin (FZJ) T.L. Grimm, W. Hartung, M. J. Johnson, M.S.
Meidlinger, J. Popielarski (NSCL)
magnetic performance of a half-reentrant cell shape is similar to that of a fully reentrant cavity, but a multi-cell halfreentrant
cavity can be cleaned using traditional techniques. We present the results of structural analyses of the
half-reentrant cavity for the mid-cell, single-cell, and multi-cell cases. The analysis includes the static and dynamic
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