Ion Thruster Contamination Test Facility

NASA Glenn Research Center
Space Environment and Experiments Branch

Ion Thruster Contamination Test Facility

Produces controlled contamination on material surfaces to study the effects of contamination.
Contamination produced by electric arc between two carbon electrodes.
Quantity of contamination is measured by the contamination thickness, the duration of the carbon arc, the mass loss of the electrodes, and/or monitoring electrical resistance.
Process occurs in vacuum inside a bell jar.

The carbon arc is powered by 15 kV, 60mA, 60-Hertz alternating current, which is transformed from 120V, 60-Hertz alternating current via a neon sign transformer.
The pressure in the bell jar is in the range of 10-6 to 10-5 mtorr during carbon arcing, and 10-7 to 10-6 mtorr without carbon arcing.
The resistance of the material to be contaminated can be monitored during the arcing process.
The voltage to measure the resistance can be in the 1-5000V range.
The carbon arc can continue for more than one hour, producing more than 1000 Å (Angstrom) of contamination.

Experimentally determine the effectiveness of the shadow shields to be used to protect ion engine’s insulators/isolators from contamination.
Experimentally determine the effects of contamination on materials having various surface morphologies.
Experimentally determine the “contamination efficiency,” or the percent of particles impacted on the surface that do not bounce away.

Study of contamination effects by materials other than carbon if other materials are used as the electrode materials.