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Satellite Charge Control


Electric Propulsion and other experiments with charge control

My work in satellite charge control started with my thesis work at UCSD.  Much of the focus was on ATS-6, with some illustrations here:

Image 1Image 2

The above two figures show the ATS-6 Ion Engine experiments.  The one on the left is the short operation in June, 1974.  This image shows the data from the EW detector - data from the NS detector are given in the article.  The one one the right is the 4.5 day operation in October.

There were a handful of formal and informal pubs on active charge control.  Two were published in 1981 in the Journal of Spacecraft and Rockets.  Subsequently, I was asked to do a review article, which ended up mostly being a combination of the first 2 papers, but I used the opportunity to add an unpublished ATS-5 ion beam experiment, and the results of one of the SCATHA electron-gun tests in eclipse.

Modification of Spacecraft Potentials by Thermal Electron Emission on ATS-5

Modification of Spacecraft Potentials by Plasma Emission on ATS-6

Experiments In Charge Control At Geosynchronous Orbit (1985)

As I was finishing up at San Diego, Elden and I had this conference publication, which includes the ATS-5 ion gun tests. Experiments on Regulation of Electric Charge on Space Vehicles

There is a contract report by myself and Elden Whipple from 1979 that includes all the grungy details on how the cesium ion engine experiments were done, and a lot of the results.  There is also a fair amount of info on Differential Charging Observations.

Not a refereed publication - but a pretty good review, anyway, from an invited talk at a 1989 conference in Huntsville: Current Limiting Mechanisms In Electron And Ion Beams Experiments.  Some material which was never published elsewhere is given here.  Conference was the "First Workshop on Current Collection from Space Plasmas, held at UAH, April 24-25, 1989.

We did a lot of work with the SCATHA electron guns.  One of the really perverse things that was observed, during a sequence of observations with the 50-eV beam setting, was return electron fluxes at 70 eV.  We had real-time printout from the UCSD instruments, so we knew this was occurring.   Herb Cohen and I spent a lot of time during the operations discussing whose calibration was off.  

The work was published in an odd venue - the Journal of Electrostatics.  I forget why - some sort of special issue, or some such. Electron Beam Experiments at High Altitudes  (I don't have the original spectrograms, so I used some alternate color spectrograms I had to rebuild the article).

Application of charge control technology to improve plasma measurements was the next step. (ESA/Cluster and Polar payloads)

I was really interested in the question about electromagnetic waves during active experiments.  This was at least in part from a contamination concern, but it seemed like a really good venue for studying basic plasma physics.  I'm pretty sure most of what we ended up studying was artifacts in the electron and ion sources.    Just before ISEE-1 re-entered, we got permission to exercise the electron guns for the first time in a decade.  (Something about the first time they were operated, Lou Frank, and some badly saturated detectors. It may be that Forest Mozer laughed about it.....)   I got a NASA guest-investigator proposal to do this, in fact.  We only analyzed a portion of the data - Roger Anderson was pre-occupied with building the Geotail instrument, as I recall.

Plasma_Wave_Observations_During_Electron_Gun_Experiments_on_ISEE

Electron gun and ion gun operations on SCATHA were also studied.

The DE-1 aperture bias work is here: Passive Charging  (DE-1)