Experimental Study of the Mini-Helicon Thruster
Abstract
An experimental program to develop and test a mini-helicon thruster is described. The helicon discharge was designed and built in several different configurations using low- and high-current electromagnets. The program was designed to address several objectives: (i) to achieve a high coupling of RF-power to plasma and efficient acceleration to >20km/sec; (ii) to evaluate the scaling relations between power density, flow rates and B-field strength; (iii) to demonstrate operation with common molecular and atomic gases, and mixtures; (iv) to provide detailed characterization of the performance using spectroscopic and invasive techniques; (v) to experimentally demonstrate variable specific impulse capability. These objectives were successfully achieved. Stable discharges with well-collimated plume exhaust were achieved for argon (Ar), nitrogen (N2), mixtures of Ar and N2, and air. The parameters of the plasmas were measured using high-resolution spectroscopic and in-situ diagnostics, including super-fine emission line structure and isotopic shift of a seeded impurity. Plasma plume flow velocities in the 10 to 40km/sec interval were measured, and plume acceleration could be easily varied by altering applied RF-power or propellant flow rate. Very high, approx. 4MW/(square meter), power density throughput has been achieved in a steady-state regime. Operation with permanent magnets was attempted as well, including a magnetic nozzle and the possibility of a double layer formation. The experimental program thus demonstrated the potential of the mini-helicon discharge as an excellent space thruster design, given its high throughput, absence of internal electrodes and cathodes, potentially long life time, very low divergence of the plasma plume, flexible choice of propellants, and variable specific impulse.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2008
- Accession Number
- ADA502975
Entities
People
- Jean-luc Cambier
- Oleg Batishchev
Organizations
- Massachusetts Institute of Technology