Ionization Instabilities in Positively Biased Spacecrafts at Low Earth Orbit.

L. Conde^a) , C. Ferro-Fontán^b) and E. Joliet^b)

a) Dep. Física Aplicada, E.T.S.I Aeronáuticos.U. Politécnica de Madrid, 28040 Madrid (Spain).

b) Dep. Astronomía y Geodesia. Fac. CC. Matemáticas.U. Complutense de Madrid, 28040 Madrid, (Spain).

Abstract

Outgassing and/or operation of spacecrafts in low Earth orbits could trigger electric dischargues or ionization instabilities within the electron collecting plasma sheath attached to the vehicle. 

In positively biased payloads, the attracted electrons are accelerated in the plasma sheath voltage drop up to energies exceeding the ionization potential of the enhanced neutral background (water vapor or cold molecular nitrogen).

Existent work is reviewed and new analytical results, that make use of a more realistic ionization term are presented. Our results suggest that this sheath-induced ionization has been underestimated in previous models, as indicated by several on ground experiments. 

Laboratory efforts addressed to verify our calculations and the predicted enhancement of local ionization will be discussed, as well as a comparison with previous results of several experiments in space.

Workshop on Multipactor, RF and DC

Corona and Passive InterModulation in Space

RF Hardware,


4-6 September 2000

ESTEC Noordwijk  The Netherlands.

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