Electric thruster models for multimegawatt nuclear electric propulsion mission design

Abstract

Three types of electric thrusters currently under development at JPL have potential to support future missions which utilize multimegawatt nuclear elecUic propulsion. These electric thrusters are the electron bombardment ion thruster, the magnetoplasmadynamic (MID) thruster, and the electron-cyclotron-resonance (ECR) thruster. The electron bombardment ion thruster is a relatively mature technology which has been developed for operation at kilowatt power levels but will require new development for application in the multimegawatt regime. The MPD engine represents a technology which may be very well suited to steady-state multimegawatt applications but which has been limited to sub-scale (100's ofkW) and pulsed (MW) testing thus far. The ECR plasma engine represents a class of very promising new concepts which are still in the basic research phase of development, but which may possess important fundamental advantages over other electric thruster technologies. In this paper, models of these thrusters are described and used to make projections of thruster specific mass, efficiency, and power handling capacity for operation in the multimegawatt regime.

Optimization of a coaxial electron cyclotron resonance plasma thruster with an analytical model

“…In the presence of complicated source geometries and magnetic field topologies, as well as nonuniform plasmas, the microwave propagation and absorption process is very complex, and the ECR phenomenon is still an active area of research. 13 A plasma is created inside the thruster by injecting and ionizing a neutral gas, and with sufficient input power, a high density plasma can be produced. A diverging magnetic field is applied using either a set of permanent magnets, or a coil, and plasma expansion in the resulting magnetic nozzle occurs outside the thruster.…”

“…9 Two typical examples of cathodeless-electrodeless plasma thrusters are the Helicon Plasma Thruster (HPT) 10,11 and the Electron Cyclotron Resonance (ECR) plasma thruster. 12,13 They are based on the excitation of a plasma by radio-frequency (rf) waves. The difference between HPT and ECR thrusters comes from the mechanism of energy transfer to the plasma.…”