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Title: Maintenance and operation procedure, and feedback controls of the J-PARC RF-driven H{sup −} ion source

In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second stage requirements of an H{sup −} ion beam of 60mA within normalized emittances of 1.5πmm•mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup −} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). The maintenance and operation procedure to minimize the plasma chamber (PCH) replacement time on the beam line, which is very important to maximize the J-PARC beam time especially for an antenna failure, is presented in this paper. The PCH preserved by filling argon (Ar) gas inside after pre-conditioning including pre-cesiation to produce the required beam at a test-stand successfully produced the required beam on the beam line with slight addition of cesium (Cs). The methods of the feedback controls of a 2MHz-RF-matching, an H{sup −} ion beam intensity and the addition of Cs are also presented. The RF-matching feedback by using two vacuum variable capacitors (VVCs) and RF-frequency shift produced the almost perfect matching with negligibly small reflected RF-power. The H{sup −} ion beam intensity was controlled within errors of ±0.1mA bymore » the RF-power feedback. The amount of Cs was also controlled by remotely opening a Cs-valve to keep the RF-power lower than a settled value.« less
Authors:
; ; ; ; ;  [1]
  1. J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)
Publication Date:
OSTI Identifier:
22391416
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1655; Journal Issue: 1; Conference: NIBS 2014: 4. International Symposium on Negative Ions, Beams and Sources, Garching (Germany), 6-10 Oct 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANTENNAS; ARGON; BEAM EMITTANCE; CAPACITORS; CESIUM; FEEDBACK; HYDROGEN IONS 1 MINUS; ION BEAMS; ION SOURCES; J-PARC; MAINTENANCE; NEUTRON SOURCES; OPERATION; PLASMA; RF SYSTEMS; SPALLATION