Title

Progress On The Met (Microwave Electro-Thermal) Thruster Using Water Propellant

Abstract

The MET thruster uses a vortex stabilized, electrodeless microwave discharge to heat propellant gas for propulsion. Because it is electrodeless, it can run on a variety of propellants , including water vapor. Progress on the MET Thruster using water vapor as a propellant is described. Operation of the MET with water vapor propellant in a short pulse mode was performed and average Isp was measured over the pulse. The average Isp was found to asymptote to approximately 900 seconds for pulse lengths of 50 seconds or more, in agreement with earlier measurements, and to be much less for pulses of 20 seconds or less. The asymptotic behavior is explained by a two-component model of mixed plasma and neutral gas inside the MET where the mass flow is dominated by neutral gas and the power flow is dominated by the plasma component with collisional momentum transfer between flows. The asymptotic behavior is then explained as a drag-up of the neutral gas flow to high speed by friction with the plasma flow. The high Isp observed for water is found by McBride Code runs to be consistent with 8000K stagnation temperatures and recombining flow in the experimental nozzle expansion ratio of 216. The recombination of the extremely reactive atomic hydrogen and hydroxol radical, resulting from thermal decomposition of the water in the microwave arc, is found to add significant energy to the flow and to explain the high observed I sp. Based on this and other research it appears that the MET with water propellant forms a propulsion system of high potential for many space missions.

Publication Date

1-1-2006

Publication Title

Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference

Volume

10

Number of Pages

8179-8186

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.2514/6.2006-5179

Socpus ID

34249279801 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/34249279801

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