IPAC2013 - List of Authors (Fan, K.)

Paper	Title	Page
MOPWA004	Development of a Non-inductive Ceramic Resistor	669
	T. Sugimoto, K. Fan, K. Ishii, H. Matsumoto KEK, Ibaraki, Japan K. Abe Hitachi Haramachi Electronics Co. Ltd., Hitachishi, Ibaraki, Japan S. Fukuoka University of Tsukuba, Graduate School of Pure and Applied Sciences,, Tsukuba, Ibaraki, Japan
	Non-inductive ceramic resistors, based on alumina and carbon, are used for impedance matching in the circuit of the J-PARC main ring injection kicker system. The kickers were installed in December 2011, and have been in operation successfully since then. However, discharges at the edge of the ceramic bulk were observed after several weeks’ operation, which increase resistance from O(100) to O(1M). Investigation indicates that poor contact with the rough surface of the ceramic bulk due to irregular shaped spots causes micro-gaps, which trigger the discharge. In order to improve the contact, one type of brazing technology has been experimentally applied to one resistor. Another resistor had an annealed thin copper plate inserted, and both resistors were tested and compared. In this paper, we will describe details of the development of the resistors and give future prospects.

MOPWA009	Development of a Fast Compensation Kicker System for J-PARC Main-ring Injection	684
	S. Fukuoka University of Tsukuba, Graduate School of Pure and Applied Sciences,, Tsukuba, Ibaraki, Japan K. Fan, K. Ishii, H. Matsumoto, T. Sugimoto KEK, Ibaraki, Japan
	Injection system of J-PARC main ring employs four lumped kickers to deflect the incoming beam. The residual field caused by tail and reflection of excitation current increases the closed beam orbit leading to particle loss in high power operation. A correction method using a fast kicker system to compensate the remaining angle is being developed. Doe to the narrow bunch spacing, transmission line kicker is selected to satisfy requirements of fast rise and fall time. The kicker magnet uses ceramic capacitors instead of parallel metal plates to make the magnet compact and reduce the stray inductance. Capacitors are installed in vacuum chamber. A very thin core is used to reduce distributed inductance. A bandwidth is calculated as 160 MHz. A Marx generator using FET switches has been studied, which is able to produce fast rise and fall time as 50 ns. Any pulse shape is generated by choosing switches to fire. A prototype magnet and a power supply have been fabricated for parameters test. In this paper, we will report the details of the system design, analyze the measurement results and give future prospects.

WEPEA015	Possibility Study of High Repetition Rate Operation of JPARC Main Ring	2528
	K. Fan, S. Igarashi, K. Ishii, T. Koseki, M. Uota KEK, Ibaraki, Japan
	The original design of JPARC main ring is to provide high beam power of 750 kW with machine repetition rate of 0.3 Hz. However, the severe space charge effects at low injection energy limit the beam intensity. In order to raise the beam power to the design limit, one logical way is to increase the repetition rate. However, the resulting eddy current in the laminations and pipes may impair the field quality of all magnets. In addition, the activation of beam pipe becomes severer in high beam power operation. Titanium beam pipe is proposed to replace the stainless steel pipe to reduce the activation and decrease the decay time. However, titanium has lower resistivity, severer eddy current effects are expected. The studies investigate the eddy current effects on field quality of the main dipole, quadrupole and sextupole magnets.

WEPEA016	Upgrade Study of JPARC Main Ring Fast Extraction Septa System	2531
	K. Fan, K. Ishii, H. Matsumoto, N. Matsumoto, Y. Morita KEK, Ibaraki, Japan
	The JPARC main ring fast extraction (FX) system has two functions, deliver high power beam to the neutrino experimental facility and dump the beam at any time in case of hardware failures. The present FX system consists of five pair of bipolar kickers and eight pair of bipolar septa. In order to raise the beam power to the design limit, both the beam intensity and the repetition rate will increase gradually. The FX system needs to be upgraded to satisfy the new requirements. The upgrade includes FX orbit optimization and new design of devices. Firstly, the conventional multi-turn low-field septa will be replaced by eddy current type septa. Several configurations of the new design has been studied to realize the requirements of thinner septum, higher field quality, lower leakage and higher mechanical stability. To provide sufficient flat top field for the FX beam, superposition of 3rd harmonic pulse has been employed.

Paper

Title

Page

Development of a Non-inductive Ceramic Resistor

669

T. Sugimoto, K. Fan, K. Ishii, H. Matsumoto
KEK, Ibaraki, Japan
K. Abe
Hitachi Haramachi Electronics Co. Ltd., Hitachishi, Ibaraki, Japan
S. Fukuoka
University of Tsukuba, Graduate School of Pure and Applied Sciences,, Tsukuba, Ibaraki, Japan

Non-inductive ceramic resistors, based on alumina and carbon, are used for impedance matching in the circuit of the J-PARC main ring injection kicker system. The kickers were installed in December 2011, and have been in operation successfully since then. However, discharges at the edge of the ceramic bulk were observed after several weeks’ operation, which increase resistance from O(100) to O(1M). Investigation indicates that poor contact with the rough surface of the ceramic bulk due to irregular shaped spots causes micro-gaps, which trigger the discharge. In order to improve the contact, one type of brazing technology has been experimentally applied to one resistor. Another resistor had an annealed thin copper plate inserted, and both resistors were tested and compared. In this paper, we will describe details of the development of the resistors and give future prospects.

MOPWA009

Development of a Fast Compensation Kicker System for J-PARC Main-ring Injection

684

S. Fukuoka
University of Tsukuba, Graduate School of Pure and Applied Sciences,, Tsukuba, Ibaraki, Japan
K. Fan, K. Ishii, H. Matsumoto, T. Sugimoto
KEK, Ibaraki, Japan

Injection system of J-PARC main ring employs four lumped kickers to deflect the incoming beam. The residual field caused by tail and reflection of excitation current increases the closed beam orbit leading to particle loss in high power operation. A correction method using a fast kicker system to compensate the remaining angle is being developed. Doe to the narrow bunch spacing, transmission line kicker is selected to satisfy requirements of fast rise and fall time. The kicker magnet uses ceramic capacitors instead of parallel metal plates to make the magnet compact and reduce the stray inductance. Capacitors are installed in vacuum chamber. A very thin core is used to reduce distributed inductance. A bandwidth is calculated as 160 MHz. A Marx generator using FET switches has been studied, which is able to produce fast rise and fall time as 50 ns. Any pulse shape is generated by choosing switches to fire. A prototype magnet and a power supply have been fabricated for parameters test. In this paper, we will report the details of the system design, analyze the measurement results and give future prospects.

WEPEA015

Possibility Study of High Repetition Rate Operation of JPARC Main Ring

2528

K. Fan, S. Igarashi, K. Ishii, T. Koseki, M. Uota
KEK, Ibaraki, Japan

The original design of JPARC main ring is to provide high beam power of 750 kW with machine repetition rate of 0.3 Hz. However, the severe space charge effects at low injection energy limit the beam intensity. In order to raise the beam power to the design limit, one logical way is to increase the repetition rate. However, the resulting eddy current in the laminations and pipes may impair the field quality of all magnets. In addition, the activation of beam pipe becomes severer in high beam power operation. Titanium beam pipe is proposed to replace the stainless steel pipe to reduce the activation and decrease the decay time. However, titanium has lower resistivity, severer eddy current effects are expected. The studies investigate the eddy current effects on field quality of the main dipole, quadrupole and sextupole magnets.

WEPEA016

Upgrade Study of JPARC Main Ring Fast Extraction Septa System

2531

K. Fan, K. Ishii, H. Matsumoto, N. Matsumoto, Y. Morita
KEK, Ibaraki, Japan

The JPARC main ring fast extraction (FX) system has two functions, deliver high power beam to the neutrino experimental facility and dump the beam at any time in case of hardware failures. The present FX system consists of five pair of bipolar kickers and eight pair of bipolar septa. In order to raise the beam power to the design limit, both the beam intensity and the repetition rate will increase gradually. The FX system needs to be upgraded to satisfy the new requirements. The upgrade includes FX orbit optimization and new design of devices. Firstly, the conventional multi-turn low-field septa will be replaced by eddy current type septa. Several configurations of the new design has been studied to realize the requirements of thinner septum, higher field quality, lower leakage and higher mechanical stability. To provide sufficient flat top field for the FX beam, superposition of 3rd harmonic pulse has been employed.