Ion Velocity Phase Space Studies of the VASIMR Engine Exhaust Plasma
Abstract
The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power engine capable of Isp/thrust modulation at constant power. The plasma is produced by helicon discharge. The bulk of the energy is added by ion cyclotron resonance heating (ICRH.) Axial momentum is obtained by adiabatic expansion of the plasma in a magnetic nozzle. Thrust/specific impulse ratio control in the VASIMR is primarily achieved by the partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. Ion dynamics in the exhaust were studied using probes, gridded energy analyzers (RPAÂ's), microwave interferometry and optical techniques. This paper will focus on the RPA data. We will examine the ion dynamics in a deuterium exhaust plasma using ∼9 kW of RF power to the helicon ionization stage and varying power levels to the ICRH acceleration stage. Ion heating of ∼70 eV/ion/kW of applied ICRH has been demonstrated. Results also confirm conversion of transverse ion motion to axial motion.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2004
- Bibcode:
- 2004APS..DPPPM2004B