Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations

Details Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations

Dec 2002

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agufmsm51b0519d&link_type=abstract

American Geophysical Union, Fall Meeting 2002, abstract #SM51B-0519

Physics

2722 Forecasting, 2753 Numerical Modeling, 2788 Storms And Substorms, 7855 Spacecraft Sheaths, Wakes, Charging

Scientific paper

We are using the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzer (MPA) dataset to determine the best spectral representation of the charged particle environment for calculating spacecraft potential during magnetospheric substorms. For 12 years LANL has been accumulating measurements of electron and proton spectra from MPA instruments aboard a series of geosynchronous satellites. These data provide both a plasma characterization and the potential of the instrument ground. Here we focus on data during eclipse periods in Sept. 2001, containing 970 measurements of charging to potentials ranging from 3 V to nearly 10 kV. Our ability to predict and "postdict" charging has suffered from both a lack of reliable secondary emission and backscattered electron yields and poor characterization of the plasma environment. One difficulty lies in the common practice of fitting the plasma data to a Maxwellian or Double Maxwellian distribution function, which may not represent the data well for charging purposes. The net current to the spacecraft is the sum of the incident electron and ion fluxes, secondary and backscattered electron fluxes, and photoelectron flux. The integral of the incident spectrum against the yield functions gives the secondary and backscattered fluxes. At equilibrium, the net current is zero. We calculate the spacecraft potential using the measured fluxes, either directly or through a fit, with appropriate correction for the difference between the measured and postulated potential. The ratio of the calculated to the measured potential tests the accuracy of the net flux calculation. The potential computed using the measured fluxes and the best available material properties of graphite carbon, with a secondary electron escape fraction of 81%, is within a factor of three of the measured potential for nearly all the data. Using a Kappa function fit to the electron distribution and a Maxwellian function fit to the ion distribution gives similar agreement. We present the accuracy of chassis potential calculations using a variety of fits to the measured spectra. These functions will be available for implementation in spacecraft charging codes such as the SEE Spacecraft Charging Handbook and NASCAP-2K.

Affiliated with

Also associated with

No associations

Rating

Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1438915