LINAC2014 - List of Authors (Naito, F.)

Paper

Title

Page

Adjustment of the Coupling Factor of the Input Coupler of the ACS Linac by a Capacitive Iris in J-PARC

264

J. Tamura, H. Ao, K. Hirano, Y. Nemoto, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
H. Asano
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
F. Naito, K. Takata
KEK, Ibaraki, Japan

Annular-ring Coupled Structure (ACS) cavities have been installed to increase the beam energy of the Japan Proton Accelerator Research Complex (J-PARC) linac from 181 to 400 MeV in the maintenance period of 2013. Some of the pillbox type input couplers with a ceramic window to the ACS cavity have a larger coupling factor than the target value by an avoidable manufacturing error. To adjust the coupling factor, a capacitive iris was introduced in the rectangular waveguide near the coupler. As a result, it has been confirmed that the iris decreases the coupling factor to a target value without any significant increase in temperature and in a discharge rate during high-power operation. In this paper, the design procedure of the capacitive iris and the result of the coupling factor adjustment are presented.

TUPP070

Status and Recent Modifications to 324-MHz RF Source in J-PARC LINAC

587

M. Kawamura, Y. Fukui, K. Futatsukawa, F. Naito
KEK, Ibaraki, Japan
E. Chishiro, K. Hasegawa, F. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan
T. Hori
JAEA, Ibaraki-ken, Japan

This paper describes the present status of and the recent modifications to the 324-MHz RF source in the J-PARC linac. The recovery from the Great East Japan Earthquake Disaster, the status of the 324-MHz klystrons, the failure of 3 high-voltage transformers (HVTRs), and the discharge suppression for the anode-modulators are described.

Poster TUPP070 [0.660 MB]

TUPP073

Study of the ACS Cavity Without a Bridge Cavity

596

TUPOL05

use link to see paper's listing under its alternate paper code

F. Naito, K. Takata
KEK, Ibaraki, Japan
H. Ao, K. Hasegawa, K. Hirano, T. Morishita, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan

J-PARC has installed the Annular-ring Coupled Structure (ACS) linac to increase the beam energy up to 400 MeV. One ACS module is composed of two accelerating tanks which are coupled by the bridge cavity. The bridge cavity simplifies the handling of the multi-tank system. While it is possible to feed the RF power into the each tanks directly with the power divider and the phase shifter instead of the bridge cavity. The rf properties of the ACS linac with the direct rf-power supply system has been measured by using the low power model made of aluminum. The measured results are described in the paper.

Slides TUPP073 [5.042 MB]

TUPP095

High-Power Test Results of the RFQ III in J-PARC Linac

649

T. Morishita, K. Hasegawa, K. Hirano, Y. Kondo, H. Oguri, S. Yamazaki
JAEA/J-PARC, Tokai-mura, Japan
T. Hori
JAEA, Ibaraki-ken, Japan
F. Naito, T. Sugimura, A. Takagi
KEK, Ibaraki, Japan

The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The beam energy of the linac has been upgraded from 181MeV to 400MeV in 2013. For the beam current upgrade, the new frontend (RF ion source, RFQ, chopping system) installation is scheduled in summer 2014 for 1MW operation at RCS. The RFQ III, which is designed for 50mA beam acceleration from 0.05MeV to 3MeV, has been fabricated and the high-power test has started at April 2013 at the test station in the J-PARC. The test station consists of the ion source, the LEBT, the RFQ, and the diagnostics devices. The nominal RF power and RF duty of the RFQ III are 380kW and 3%(0.6ms and 50Hz), respectively. The high-power conditioning reached to the 120% of the nominal power with 1.5% (0.6ms, 25Hz) RF duty within 24 hours. Then, we performed the beam operation at the test station and measured beam parameters after the RFQ III. The results of the high-power conditioning and the stability of the RFQ operation with beam will be discussed.

Paper	Title	Page
MOPP090	Adjustment of the Coupling Factor of the Input Coupler of the ACS Linac by a Capacitive Iris in J-PARC	264
	J. Tamura, H. Ao, K. Hirano, Y. Nemoto, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan H. Asano Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan F. Naito, K. Takata KEK, Ibaraki, Japan
	Annular-ring Coupled Structure (ACS) cavities have been installed to increase the beam energy of the Japan Proton Accelerator Research Complex (J-PARC) linac from 181 to 400 MeV in the maintenance period of 2013. Some of the pillbox type input couplers with a ceramic window to the ACS cavity have a larger coupling factor than the target value by an avoidable manufacturing error. To adjust the coupling factor, a capacitive iris was introduced in the rectangular waveguide near the coupler. As a result, it has been confirmed that the iris decreases the coupling factor to a target value without any significant increase in temperature and in a discharge rate during high-power operation. In this paper, the design procedure of the capacitive iris and the result of the coupling factor adjustment are presented.

TUPP070	Status and Recent Modifications to 324-MHz RF Source in J-PARC LINAC	587
	M. Kawamura, Y. Fukui, K. Futatsukawa, F. Naito KEK, Ibaraki, Japan E. Chishiro, K. Hasegawa, F. Sato, S. Shinozaki JAEA/J-PARC, Tokai-mura, Japan T. Hori JAEA, Ibaraki-ken, Japan
	This paper describes the present status of and the recent modifications to the 324-MHz RF source in the J-PARC linac. The recovery from the Great East Japan Earthquake Disaster, the status of the 324-MHz klystrons, the failure of 3 high-voltage transformers (HVTRs), and the discharge suppression for the anode-modulators are described.
	Poster TUPP070 [0.660 MB]

TUPP073	Study of the ACS Cavity Without a Bridge Cavity	596
TUPOL05	use link to see paper's listing under its alternate paper code
	F. Naito, K. Takata KEK, Ibaraki, Japan H. Ao, K. Hasegawa, K. Hirano, T. Morishita, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan
	J-PARC has installed the Annular-ring Coupled Structure (ACS) linac to increase the beam energy up to 400 MeV. One ACS module is composed of two accelerating tanks which are coupled by the bridge cavity. The bridge cavity simplifies the handling of the multi-tank system. While it is possible to feed the RF power into the each tanks directly with the power divider and the phase shifter instead of the bridge cavity. The rf properties of the ACS linac with the direct rf-power supply system has been measured by using the low power model made of aluminum. The measured results are described in the paper.
	Slides TUPP073 [5.042 MB]

TUPP095	High-Power Test Results of the RFQ III in J-PARC Linac	649
	T. Morishita, K. Hasegawa, K. Hirano, Y. Kondo, H. Oguri, S. Yamazaki JAEA/J-PARC, Tokai-mura, Japan T. Hori JAEA, Ibaraki-ken, Japan F. Naito, T. Sugimura, A. Takagi KEK, Ibaraki, Japan
	The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The beam energy of the linac has been upgraded from 181MeV to 400MeV in 2013. For the beam current upgrade, the new frontend (RF ion source, RFQ, chopping system) installation is scheduled in summer 2014 for 1MW operation at RCS. The RFQ III, which is designed for 50mA beam acceleration from 0.05MeV to 3MeV, has been fabricated and the high-power test has started at April 2013 at the test station in the J-PARC. The test station consists of the ion source, the LEBT, the RFQ, and the diagnostics devices. The nominal RF power and RF duty of the RFQ III are 380kW and 3%(0.6ms and 50Hz), respectively. The high-power conditioning reached to the 120% of the nominal power with 1.5% (0.6ms, 25Hz) RF duty within 24 hours. Then, we performed the beam operation at the test station and measured beam parameters after the RFQ III. The results of the high-power conditioning and the stability of the RFQ operation with beam will be discussed.