Noguchi S.

Paper	Title	Page
TUP60	High Power Input Couplers for the STF Baseline Cavity System at KEK	270
	E. Kako, H. Hayano, S. Noguchi, T. Shishido, K. Watanabe, Y. Yamamoto KEK
	An input coupler, which consists of a cold coupler and a warm coupler, has two Tristan-type coaxial disk rf windows. There is no tuning mechanism for varying coupling for simplicity and cost reduction. Fabrication of four input couplers was completed, and the rf measurements with low rf power were carried out. The input couplers were assembled with coupling waveguides and doorknob-type transitions, and they were installed in a high power rf system. High power tests of four input couplers were carried out in the test stand with a 5 MW pulsed klystron. Rf processing up to 1.0 MW in a 1.5 msec and 5 Hz operation (1.9 MW in a short pulse) was successfully performed without any troubles. One cavity for the STF Phase-0.5 was assembled with an input coupler and a tuning system, and the cavity was installed in one of the 6m-cryomodules. Rf processing of the input coupler in the cryomodule was carried out at room temperature up to 250 kW in a 1.5 msec step pulse and 5 Hz operation. First cool-down and high power test of the cryomodule had been started in October, 2007.
WE303	New Tuners for ILC Cavity Application
	S. Noguchi KEK
	Abstract and paper not submitted.
	Slides(PDF)
WEP10	Vertical test results on the STF baseline 9-cell cavities at KEK	453
	E. Kako, H. Hayano, S. Noguchi, T. Shishido, K. Umemori, K. Watanabe, Y. Yamamoto KEK H. Sakai, K. Shinoe ISSP, Univ.  of Tokyo S. I. Moon POSTECH Q. J. Xu IHEP, CAS
	The STF-Baseline superconducting cavity system, which includes four TESLA-type 9-cell cavities, input couplers and frequency tuners, has been developed for the future ILC project. A main improvement in the cavity system is a very stiff design in a He vessel and a cavity tuning system, which can relax a cavity deformation due to Lorentz force. Making clear the performance level of four 9-cell cavities, which were fabricated by a Japanese company and were prepared by existent infrastructures at KEK, is the most important purpose in the whole vertical test. Total 14 vertical tests on four 9-cell cavities were carried out repeatedly. The obtained Eacc,max in the final performance was 29.4 MV/m in the #2 cavity, and the others are 20.8, 20.5 and 20.2 MV/m, where the Qo values higher than 1x1010 was achieved in all cavities. Peculiar phenomena, like increasing of Qo values with higher Eacc or very slow degradation of Qo values, were observed in the vertical tests. Summary of the vertical test results on four 9-cell cavities is described in this paper.
WEP13	Cavity diagnostic system for the vertical test of the baseline SC cavity in KEK-STF	464
	Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, T. Shishido, K. Umemori, K. Watanabe KEK H. Sakai, K. Shinoe ISSP, Univ.  of Tokyo S. I. Moon POSTECH Q. J. Xu IHEP, CAS
	Four STF-Baseline superconducting cavities were fabricated from 2005 to 2006. They were named BL1, 2, 3 and 4. The feature is that these cavities have the stiffer structure than TESLA cavity. From Feb/2006 to Feb/2007, the vertical tests were done totally 14 times at KEK. These cavities were re-processed and measured repeatedly. The surface treatment processes are composed of Centrifugal Barrel Polish (CBP), Electro-Polish (EP) and High Pressure Rinsing (HPR). And, HF or H2O2 rinsing were added as the additional process later. In the vertical tests, a monitoring system was introduced to search the heating spot on the equator and to check the radiation level around the cavity. It is composed of the carbon resistors and the PIN photo diodes. They were attached on the equator of each cell every 90 degree, a few resistors around the HOM couplers and a few diodes on the top and bottom flanges of the cavity. MX-100 (YOKOGAWA) for the carbon resistors and NR-1000 (KEYENCE) for the PIN photo diodes are used as the data logger. The sampling time is 100 or 200msec. The heating spot was successfully observed during the test. The appearance of that on the equator was coincident with the quench of the cavity. On the other hand, the diodes were useful for checking the presence or absence of the field emission and they also were useful for monitoring the radiation level during the RF processing. The mapping display was introduced to identify the location. Consequently, it is conceivable that the quality of the electron beam welding was somewhat poor, when the dumbbells were connected.
WEP30	New HOM coupler design for ERL injector at KEK	530
	K. Watanabe, H. Hayano, S. Noguchi, E. Kako, T. Shishido KEK
	The development of superconducting cavities and cavity package for ILC and ERL project is under way at STF (Superconducting RF Test Facility) in KEK. The TESLA-style coaxial HOM couplers have a problem at CW operation, which it is pick-up probe and inner conductor heating of HOM coupler. The pick-up probe heating was observed at vertical tests. The probe heating study for CW operation (changing pick-up probe geometry and probe gap) tried at vertical tests by using the KEK STF Baseline 1.3 GHz 9-cell superconducting cavity, and simulated by using HFSS code ver9.1 for estimate the relation of the limit E-field of probe heating and the probe surface current. The design of proto-type coaxial HOM couplers of CW operation for ERL-injector at KEK was tried based on this information. The probe heating is generated due to the probe surface current by the RF load of accelerating mode. Therefore, as one method, it can be controlled if the RF load of accelerating mode is reduced by putting the high pass filter between the coupling loop and the notch filter. In addition, the target beam current of ERL is about 100mA, therefore, we were considered that the cooling of inner conductor of HOM coupler by liquid He. It is necessary to be expected the heating of inner conductor by RF load of accelerating mode and HOM power of excited in the beam. The design was held based on these. In this report, a design of HOM coupler for ERLinjector at KEK is presented.