Engineering topics

Grier, N.

Publications and source records attributed to Grier, N..

4 records

NASA NTRS1978

Investigation of high voltage spacecraft system interactions with plasma environments

An experimental investigation was undertaken for insulator and conductor test surfaces biased up to + or - 1kV in a simulated low earth orbit charged particle environment. It was found that these interactions are controlled by the insulator surfaces surrounding the biased conductors. For positive applied voltages the electron current collection can be enhanced by the insulators. For negative applied voltages the insulator surface confines the voltage to the conductor region. Understanding these interactions and the technology to control their impact on system operation is essential to the design of solar cell arrays for ion drive propulsion applications that use direct drive power processing.

Stevens, N. J.↗

NASA NTRS1978

Investigation of high voltage spacecraft system interactions with plasma environments

The exposure of high voltage spacecraft systems to the charged particle environment of space can produce interactions that will influence system operation. An experimental investigation of these interactions has been undertaken for insulator and conductor test surfaces biased up to plus or minus 1 kV in a simulated low earth orbit charged particle environment. It has been found that these interactions are controlled by the insulator surfaces surrounding the biased conductors. For positive applied voltages the electron current collection can be enhanced by the insulators. For negative applied voltages the insulator surface confines the voltage to the conductor region; this can cause arcing. Understanding these interactions and the technology to control their impact on system operation is essential to the design of solar cell arrays for ion drive propulsion applications that use direct drive power processing.

Stevens, N. J.↗

NASA NTRS1978

Laboratory studies of electrical properties of insulating materials

The characteristics of satellites are influenced by the electrical properties of the dielectric exterior. It was found in simulated space environment tests that the electrical conductivities of dielectrics are affected as the result of interactions with various components of the environment. The degree to which the conductivity was affected varied with material. In some instances the changes found to occur could be used to advantage, particularly if they could be enhanced. For example, the increased electrical conductivity of Kapton resulting from solar illumination could be used to advantage to eliminate the charge storage leading to electrical breakdown during magnetic substorms. Similarly the relative immunity of FEP Teflon to change from response to the space environment makes it a logical choice as a solar cell cover in a high-voltage solar array.

Nanevicz, J. E.↗

NASA NTRS1976

Conductivity effects in high-voltage spacecraft insulating materials

Laboratory measurements were performed to assess the influence of various external parameters on the conductivity properties of several typical and potential spacecraft insulating materials in a simulated space environment. The materials tested include Kapton, Teflon, quartz, and polyvinylidene fluoride. The parameters measured comprise sample thickness, temperature, applied voltage, illumination intensity and wavelength, and electron beam energy and current density. All tests were conducted in a vacuum chamber at a pressure of about one millionth Torr both with conventional optically-transparent gold front-surface electrodes and with the front surfaces of the test samples exposed directly to an electron beam. The data presented illustrate some of the complexities in electrical characteristics exhibited by the materials as a result of interactions with various conditions of their environment.

Adamo, R. C.↗