Modeling and simulation of Inductively Coupled Plasma (ICP) generation at 2 MHz frequency for RF based H^- ion source

The RF based multicusp H^- ion source with external antenna has the high operational life time and most promising method of H^- ion beam current with low emittance. In this paper a 3D simulation work of ICP discharge based on Octa-pole multicusp field confine hydrogen plasma chamber in 6 turn solenoid antenna with ferrite and filter field is presented using multiphysics Comsol simulation software. The simulation was carried out for 2 MHz RF frequency and coil current of 400 A for hydrogen gas at 5.5 x 10^-2 mbar gas pressure at different time periods. The distribution of plasma parameters, i.e. electron density, electron temperature; plasma potential inside the plasma chamber was obtained using 3D simulations. Field generated due to antenna, filter magnet and multi cusp configuration was also simulated and results show that ICP discharge equilibrium peak electron density of 1.85 x 10¹⁸ m^-3 , which occurs near the axis of plasma chamber underneath the antenna coil. This was due to the squeezing of plasma by the joint effect of electromagnetic field generated by antenna in the presence of multicusp field due to permanent magnets. Electron temperature shows variation inside the chamber and its maximum occur near the coil body was 14 eV and around 3 eV near the axis of plasma chamber. The effective current density and magnetic field induced were maximum near the antenna coil leading to higher electron temperature. Plasma potential was maximum in the centre of plasma chamber. Results obtained were found to be in agreement with the recent results reported by Linac4 group