Investigation of Ion Beam Extraction Mechanism for Higher Thrust Density of Ion Thrusters

Abstract

We have investigated ion beam extraction mechanism using two dimensional axisymmetric particle-in-cell simulations with Monte Carlo collisions (PIC/MCC) under various conditions of grid structures. The calculations are carried out for both the plasma region and the vacuum region simultaneously, where the former is 5.0 mm in radius and 10 mm in length and the latter is 6.0 mm in radius and 20 mm in length. The PIC/MCC results have shown that the ion beam current is affected by the gap distance of the grids and thickness of the screen grid, but is not affected by the hole diameter of the screen grid. Moreover, the optimum value of the difference between the hole diameter of the screen grid and that of the accelerator grid is 1.4 mm at various grid gap distances and thicknesses under the following conditions: the gas pressure is 3.2 mTorr, the absorbed power is 500 mW and the beam voltage is 1100 V.