One-Dimensional Numerical Calculation of Discharge Current Oscillations in a Hall Thruster

Abstract

A one-dimensional numerical simulation was conducted inside an anode layer type Hall thruster in order to clarify the nature of low frequency discharge oscillation in Hall thrusters. The model assumed quasi-neutrality, Maxwellian electron distribution, and classical and Bohm diffusions across magnetic field lines. Heavy species were simulated using Particle-in-Cell (PIC) method, and electrons were dealt as fluid continuum. Generalized Ohm's law was used to determine the electric potential, and an electron energy equation was solved to determine the electron temperature. As a result, we obtained discharge oscillations which were caused by ionization instability. The calculated current, its oscillations, and the stable operation range agreed with measured ones. We also succeeded to simulate the transition from the classical diffusion mode to Bohm diffusion mode by the calculation. In the discussion, it is shown that the electron energy given by the electric field has the large effect on the current oscillation. 5-9f AϕϕAAAAAAkkkkkkkkkkIIIIIIIII∂Q BϕϕϕBBBBEE EϕEEEl eϕEE,,EEEE E 0 !'%"%N!¡%INN0h2¡N.C¡$NEE0L E n n ,, n kEEEE E i !'0l2AEEN%%(%M%k%.!¡ j d !'J-EEEEN. j e !'¡4J˝8˜$NEE;REEN.L)EY kϕϕϕϕkkkkkkkkjjt lϕϕϕϕϕϕϕϕIIIIIIIIIIIIIIkEEEll. El5˜Bg3X9)3X7O8&5f2J9R6u1'Ch9)3X@l96 * 3 6e=#Bg3XAm9gM˝9)3X8&5f1!%(%M%k%.!¡M˝9)3XItLg * 4 El5˜Bg3X?7NN0hAO@.2J3X8&5f2J@hC¡%(%M%k%.!¡9)3X@l96 φϕEEEE σu e i !'EEN%¿WFM78?t σu e en !'EE;R-Cf@-N3;R¿WFM78?t σu e ei !'EE;R-%$%*%s¿WFM78?t τ ϕBBBj,,,, ν ei !'EE;R-%$%*%s¿WFM¡˜GH?t ν en !'EE;R-Cf@-N3;R¿WFM¡˜GH?t ϕϕEEEEEEEEEkkkkk E...,, e!'EE;R i!'%$%*%s n!'Cf@-N3;R