Experimental study of pulsed ion beam generated by different pulsing topology in 2.45 GHz ECR proton source

Abstract

Electron Cyclotron Resonance Ion Source (ECRIS) is used as a front end for Low Energy High Intensity Proton Accelerator (LEHIPA). A 50 keV ECRIS is designed and developed for the proton ion beam at BARC. The key requirements of the ion source are stability of ion beam, repeatability, reliability with beam emittance of 0.2 π mm mrad, and proton fraction of 90% or more. Presently LEHIPA accelerated proton beam to 3 MeV from Radio Frequency Quadrupole (RFQ) and further beam experiments are in progress. The beam acceleration from RFQ is in pulsed mode with 250 μs on time at a repetition rate of 2 Hz. The incoming beam from the ion source is of 50 keV, 4 to 5 mA at the entrance of RFQ with a beam on time of 1 ms. In this work, two different beam pulsing methods for ECRIS are experimentally investigated. One is by pulsing the extractor High Voltage (HV) with continuous plasma operation and the other is by pulsing the plasma with continuous extractor HV. The details of the experimental setup, plasma tuning, optimization, extracted beam current results, and comparison of both methods are discussed. It is concluded that for obtaining a stable pulsed ion beam, pulsing the extractor HV is a better option than pulsing the plasma.