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Title: Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20–40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, −2 to −4 kV, and 0 kV, respectively. The total ion beam current of 30–40 mA is recordedmore » on Faraday cup at 40 keV of beam energy at 600–1000 W of microwave power, 800–1000 G axial magnetic field and (1.2–3.9) × 10{sup −3} mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.« less
Authors:
; ; ;  [1] ;  [2]
  1. Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)
  2. Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)
Publication Date:
OSTI Identifier:
22255025
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 43 PARTICLE ACCELERATORS; ACCELERATORS; APERTURES; BEAM CURRENTS; BEAM EXTRACTION; BORON NITRIDES; DRILLS; ELECTRODES; ELECTRON CYCLOTRON-RESONANCE; FARADAY CUPS; ION SOURCES; MAGNETIC FIELDS; MICROWAVE RADIATION; OPTIMIZATION; PLASMA; QUARTZ