| Paper | Title | Page |
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| TPPT051 | High Power Coupler for the TESLA Superstructure Cavities | 3141 |
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Funding: U.S. Department of Energy Grant No. DE-FG02-00ER86102. More and more accelerators are built with superconducting cavities operating at cryogenic temperatures, and the probability of a ceramic window failure presents increasing problems because of the resulting contamination of the cavities surfaces and the resulting accelerating electric field degradation. A cost effective design and fabrication method for the TESLA cavities has been developed in the framework of a DOE STTR grant. This new design replaces the present TESLA cylindrical ceramic windows with two planar disc windows separated by a vacuum space and is optimized for RF input power, vacuum characteristics, and thermal properties. This novel coupler will reduce the costs of fabrication and improve the RF performance of the coupler, the vacuum between the two windows, and the cleaning procedure. Two couplers with this design have been fabricated and are presently being conditioned for testing at DESY, Germany, and LAL, France, on the RF high power testing stand and on a test cryomodule. |
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| TPPT054 | CW Operation of the TTF-III Input Coupler | 3292 |
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| Many newly proposed light sources, operating in the CW regime, are based on superconducting TESLA technology. Since this was originally developed for pulsed, 1-% duty-factor operation, it is important to determine the limitations of the TESLA cryomodule and its components when operated CW. Among the critical components is the RF input coupler. Two tests have been performed to determine the average power limit of the TTF-III system. First, room temperature tests up to 4 kW were performed at the Forschungszentrum Rossendorf. These permitted the calibration of computer codes developed to calculate the temperature distribution in the coupler. The programs then were used to make predictions for the (normal) cold operation of the coupler. At BESSY, the coupler test stand was assembled inside the HoBiCaT horizontal cryostat test facility to operate the coupler in an environment close to that of a real accelerator. The results of the two tests are presented here. | ||
| WPAT088 | Performance of TESLA Cavities After Fabrication and Preparation in Industry | 4221 |
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| In order to demonstrate cw operation of TESLA cavities in linear accelerators driving FEL applications, two TESLA cavities were manufactured and prepared by ACCEL for BESSY. After production, both cavities were prepared for vertical test at ACCEL's premises using state of the art chemical polishing and high pressure water rinsing techniques. The cavities were tested in DESY's vertical RF test installation. Accelerating gradients close to 25 MV/m were reached. One cavity was completed with a helium vessel modified for cw operation and prepared with chemical polishing, high pressure water rinsing, and assembled with the required High Power Coupler at ACCEL. The fully dressed cavity was then shipped under vacuum to BESSY and tested in the horizontal cryostat HoBiCaT. Horizontal RF test results will be presented and compared with the vertical test results. |