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Description
Low pressure, low-temperature plasma (LTP) with a spatially varying transverse magnetic filter field configuration has a wide range of applications. In such devices, the magnetic field value is low enough that it magnetizes only the electrons and not the ions and works as an electron cooler by limiting the flux of hot electrons [1]. Due to the gradient of the transverse magnetic filter field, the electron cyclotron frequencies are also changing with location and in some places it comes close to different collision frequencies. A parallel 2D-3V Particle-in-Cell Monte Carlo Collision (PIC MCC) kinetic model is developed [2, 3] to study plasma transport in a negative ion source where spatially varying transverse magnetic filter field is considered in a source geometry similar to that of ROBIN (RF Operated Beam source in India) [4]. Various collision dependent physical phenomena, having different time scales and length scales are studied. It is observed that the magnetic filter increases electron-ion and electron-electron collisions a couple of times than those in the absence of the magnetic filter. In this article, we summarize with observations based on the collision frequencies and try to understand if there are any resonant phenomena happening in the magnetic filter region which may lead to any instability and influence the cross-field transport.
References:
[1] Boeuf, J. P. et al. (2012), Physics of a magnetic filter for negative ion sources. I. Collisional transport across the filter in an ideal, 1D filter. Physics of Plasmas, 19(11).
[2] Chaudhury, B. et al. (2018). Hybrid Parallelization of Particle in Cell Monte Carlo Collision (PIC-MCC) Algorithm for Simulation of Low Temperature Plasmas. In Communications in Computer and Information Science book series (pp. 32–53). Springer, Singapore.
[3] Shah, M (2020). Computational characteristics of plasma transport across magnetic filter in ROBIN using PIC-MCC simulation. Fusion Engineering and Design, 151, 111402.
[4] Bansal, G. et al. (2013). Negative ion beam extraction in ROBIN. Fusion Engineering and Design, 88(6–8), 778–782.
Summary
Detail study on collisional transport of electrons across the low magnetic filter in the low temperature plasmas using 2D-3V PIC-MCC kinetic model.
