Feasibility study of medium-power helicon thruster

A medium-power (1.5 kW) plasma thruster based on a helicon source is considered as a candidate for primary space propulsion. A high-density plasma is produced by the use of a radio frequency (RF) transmitting antenna, which produces helicon waves to ionize a neutral gas (e.g., argon, krypton, xenon, helium or hydrogen) flowing through a tube and confined by a magnetic field. The plasma is accelerated through a potential drop created by a divergent magnetic field, giving a sudden reduction in electron density (and hence plasma potential) very close to the open end of the source tube. The plasma may then expand through a "magnetic nozzle" into the vacuum. Numerical studies are conducted by CISAS in order to investigate the physics connected with the potential drop. The analysis is conducted through a combination of 1-D and 2-D numerical codes. The PPDL code is developed and used for the 1-D analysis. The main features of the code are: hybrid Boltzmann electron/drift-kinetic ion, inclusion of dominant 2-D effects, and high computational efficiency thorough implicit non linear Boltzmann solver. The 2-D analysis is performed with XOOPIC, an open source code available from Berkeley University. The combined approach is very useful since the 1-D code is used to screen many different experimental conditions and to identify the correct boundary conditions. The 2-D code is then used to refine 1-D results. The two models, combined with a global model, specifically developed to simulate the plasma reaction inside the plasma source, are run through genetic algorithms to identify an optimal thruster configuration in the 1500-W power regime. In addition, the thruster is thermally and mechanically sized.