Engineering topics

Brandon, S. T.

Publications and source records attributed to Brandon, S. T..

3 records

NASA NTRS1985

Self-consistent simulation of plasma interactions with secondary-emitting insulators

A cylindrical particle-in-cell (PIC) plasma simulation code applicable to plasma densities encountered in low Earth orbit (LEO) is described. The simulated geometries include that of a plain disk and a disk surrounded by a dielectric. Both configurations are mounted upon a ground plate in contact with a plasma environment. Techniques allowing simulation of dielectric charging using PIC time scales are discussed. Current versus voltage characteristic curves are calculated and the results are compared to experimental data.

Brandon, S. T.↗

NASA NTRS1984

Numerical simulations of positively-biased probes and dielectric-conductor disks in a plasma

Plasma densities in the low-earth orbit range may be sufficient to cause difficulties for spacecraft operating at high voltages in this environment. The present investigation is concerned with the results of a continuing effort to develop a particle-in-cell (PIC), cylindrically-symmetric, 2-1/2 dimensional, self-consistent numerical simulation code. The simulation has the objective to explore the interactions of an ambient plasma with a conducting disk, which may be partially covered by a dielectric material. The disk and the surrounding dielectric material represent a hole in an insulator covering a conductor. Attention is given to a review of the simulation model, plain disk calculations, the disk and dielectric configuration, and the 'pinhole' effect.

Brandon, S. T.↗

NASA NTRS1981

Low-energy charged particle observations in the 5-20 Jupiter-radius region of the Jovian magnetosphere

Ion (greater than 0.5 MeV) and electron (greater than 30 keV) measurements made by the low-energy charged particle instrument during the Voyager 1 and 2 traversals of the 5-20 Jupiter-radius region of the Jovian magnetosphere are presented. The spatial morphology of particle intensities, energy spectra, and composition is emphasized. Diffusive radial transport is also discussed. The Jovian magnetosphere seemed to be much more disturbed during the Voyager 2 passage than during that of Voyager 1. Significant inbound-outbound asymmetries of the radial profiles of intensities are observed; an appropriate magnetic field model to provide closure has not been found. Low-energy electrons are not enhanced or depleted in the Io torus region except at the inner edge, about 5.2 Jupiter-radius, where they sharply decrease. This may be due to enhanced electron loss associated with a region of increased plasma density.

Armstrong, T. P.↗