Performance Parameter Analysis of a Hall Effect Thruster With Modified Bohm Parameter Model
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ORIGINAL PAPER
Performance Parameter Analysis of a Hall Effect Thruster With Modified Bohm Parameter Model Min Gyoung Cho1 · Gwanyong Jung2 · Hong-Gye Sung2 Received: 7 August 2019 / Revised: 29 January 2020 / Accepted: 25 February 2020 © The Korean Society for Aeronautical & Space Sciences 2020
Abstract The Hall effect thruster (HET) is an electric propulsion system in which electrons confined in a certain region collide with neutral particles due to the Hall effect. The neutral particles are ionized, and the ions are accelerated by the electric field to produce thrust. Thus, a Hall thruster has a simpler structure than an ion thruster. To improve the accuracy of the HET performance analysis, the energy change of electrons is predicted by considering thermal conduction. The number of ions produced by ionization and the change in electron energy via multivalent ionization are investigated. To minimize the independent variables, the boundary condition is modified after considering the physical correlation of each variable, and a semi-experimental model equation for the Bohm parameter is proposed. The performance results have greater similarity to the experimental results than those of the previous analytical model. Based on this, the performance changes according to the thruster operating conditions are predicted and compared. It is confirmed that the thrust increases by about 10–20% according to the change of propellant mass flow rate due to the increase of ion exit velocity. Keywords Hall effect thruster · Ionization · Low-temperature plasma · 1D steady equations
List of Symbols A B E e F h I I sp m m˙ n q R Te v
B
Cross area (m2) Magnetic flux density (T) Electric field (V/m) Electron charge (C) Thrust (N) Plume radial thickness (m) Current (A) Specific impulse (s) Particle mass (kg) Propellant mass flow rate (kg/s) Number density (1/m2) Heat flux (W/m2) Ionization reaction rate (m3 /s) Electron temperature (eV) Velocity (m/s) Min Gyoung Cho [email protected]
1
Research & Development, Korea Aerospace Industries, Ltd., Sacheon-si, South Korea
2
Aerospace and Mechanical Engineering, Korea Aerospace University, Gyeonggido, Korea
Greek αB Γ φ ν ωe
Bohm parameter Number density flux (1/s) Electric potential (V) Collision frequency Electron cyclotron frequency (1/s)
Subscripts ano d e i n x w
Anomalous Discharge Electron Ion Neutral x-Axis direction Wall
1 Introduction Numerical approaches for the study of the plasma flow field of Hall thrusters have been conducted with various methods. For instance, hybrid PIC method have been developed based
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International Journal of Aeronautical and Space Sciences
and the consumption rate of the neutrons are equivalent in a steady state, which is expressed using Eq. (1): dΓe dΓn dΓi − An e νi . dx dx dx
(1)
The ion momentum changes according to potential changes in the electric field (φ) and the momentum loss due to ionization [Eq. (2)]: dφ d − m i νi n e vxn . (m i vxi Γi ) −en e dx dx
Fig. 1 Schematic of a Hall thruster
(2)
In the case of the
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