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

Abstract

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 recorded 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(-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.

Emittance and proton fraction measurement in High current electron cyclotron resonance proton ion source

“…The reflected power was minimized using a four stub auto-tuner. Once the plasma discharge was established, the ion beam was extracted by biasing the extraction electrodes [1,3]. An electron suppressed movable Faraday cup was used to measure the total ion beam current.…”

“…The ion beam is extracted by biasing the extraction electrodes when the plasma is stabilized. The studies on plasma characterization, beam extraction and stable operation of the ion source have been reported earlier [2,3]. In this paper we report the measurement of two crucial beam parameters i.e.…”

“…A high current Electron Cyclotron resonance (ECR) proton ion source has been designed and developed for Low Energy High Intensity Proton Accelerator (LEHIPA) at Bhabha Atomic Research Centre (BARC) [1][2][3]. LEHIPA consists of H þ ion source at 50 keV to be accelerated to 3 MeV by Radio Frequency Quadrupole (RFQ) and to 20 MeV by an Alvarez type DTL.…”

Beam acceleration through proton radio frequency quadrupole accelerator in BARC

“…Gas Pressure (10 electrodes when the plasma is stabilized. The studies on plasma characterization, beam extraction and stable operation of the ion source have been reported earlier [6,7]. The emittance was measured using two slit emittance meter and proton fraction was measured using a magnetic mass analyzer.…”

Tailoring of microwave power density in an ECR ion source using an optimized ridge coupler

“…Microwave based Electron Cyclotron Resonance Ion Source (ECR-IS) is widely used in high energy, high intensity accelerators for applications involving radioisotope production, spallation neutron sources, accelerator driven systems, high energy physics etc, since it can produce high intensity and high charge state ion beams with low beam emittance [1][2][3][4][5][6]. A high intensity ECR proton ion source has been developed for the Low Energy High Intensity Proton Accelerator (LEHIPA) at Bhabha Atomic Research Centre (BARC), India [4][5][6]. LEHIPA consists of H+ ion source at 50 keV which is accelerated to 3 MeV by Radio Frequency Quadrupole (RFQ) and thereafter to 20 MeV by an Alvarez type DTL consisting of 4 DTL tanks of 3 m each [7][8][9].…”