| Paper |
Title |
Page |
| TUP025 |
Optimization of Surface Treatment of High-Gradient Single-Cell Superconducting Cavities at KEK
|
299 |
| |
- F. Furuta, Y. Higashi, T. Higo, I. H. Inoue, S. Kazakov, H. Matsumoto, Y. Morozumi, R. S. Orr, T. Saeki, K. Saito, M. Satoh, K. Ueno, H. Yamaoka
KEK, Ibaraki
|
|
| |
We have continued the study of a series of single cell superconducting cavities at KEK. These tests are aimed at establishing a prescription for a surface treatment that would reliably allow cavities to reach gradients in excess of 45 MV/m in vertical tests. The cavity profiles were all of the KEK Low Loss design, and were fabricated from deep drawn Niobium half shells using electron beam welding. The cavity initial surface preparation followed an established KEK procedure of centrifugal barrel polishing, high temperature annealing, light chemical polishing, electropolishing. and final a high pressure water rinse. Early results from this series test demonstrated that reaching gradients as high as 50 MV/m is feasible. However, the initial yield was of order 50%. In this paper we will discuss our studies of further improvement of the surface treatment aimed at increasing the yield.
|
|
| THP037 |
Wide-Range Frequency Compensation by Coaxial Ball-Screw Tuner
|
658 |
| |
- T. Higo, Y. Higashi, Y. Morozumi, K. Saito, K. Ueno, H. Yamaoka
KEK, Ibaraki
|
|
| |
Low-loss 9-cell 1.3GHz cavities are studied at KEK aiming at a high-gradient operation for the International Linear Collider. One of the most important issues to realize such a high gradient in a pulsed operation of super-conducting cavities is the issue of how to compensate the Lorentz detuning. The Lorentz detuning of the cavity amounts to 3kHz at 45MV/m acceleration field. None of the tuners to date have achieved this range. A coaxial ball-screw tuner was designed and proved to reach this level in the room temperature operation. The performance at liquid Nitrogen temperature is also studied. From these results, we try to evaluate the feasibility of the operation at 2K.
|
|
| THP038 |
Normal Conducting High-Gradient Studies at KEK
|
661 |
| |
- T. Higo, M. Akemoto, S. Fukuda, Y. Higashi, N. K. Kudo, S. Matsumoto, K. Takata, T. T. Takatomi, K. Ueno, K. Yokoyama
KEK, Ibaraki
|
|
| |
Normal-conducting high field studies have been pursued at XTF, a high power X-band RF facility of KEK developed for linear collider. Three traveling-wave structures developed for X-band linear collider were studied in high field of more than 70MV/m level. High-field characteristic such as field emission properties and trip rate, etc. are studied carefully as the processing proceeds. Operation at 50MV/m level was found very stable while breakdowns happened once an hour or so at more than 70MV/m, indicating the approach to some critical point. This characteristics is discussed in conjunction with various author’s trials to make a scaling law of severe breakdowns among power, pulse width and so on. Further basic studies on field/power limitation or robustness against breakdowns in various materials are planned using narrowed waveguide configuration. Unique features related to this study is also described.
|
|
| THP090 |
Initial Studies of 9-Cell High-Gradient Superconducting Cavities at KEK
|
794 |
| |
- T. Saeki, F. Furuta, H. Hayano, Y. Higashi, T. Higo, I. H. Inoue, S. Kazakov, H. Matsumoto, Y. Morozumi, R. S. Orr, K. Saito, M. Satoh, N. Toge, K. Ueno, H. Yamaoka, K. Yokoya
KEK, Ibaraki
|
|
| |
Vertical tests of single cell cavities of the KEK Low Loss "Ichiro" design have established that gradients as high as 51 MV/m are feasible in principle. We have also performed vertical tests of 9-cell cavities. The internal surface was prepared according to the prescription developed in the single cell series test. In this paper we report results on the accelerating gradients achieved so far, an investigation of the possible presence of hydrogen "Q Disease," and other high-field related studies. We also present the measurement of the higher modes of the cavities.
|
|