High Voltage Solar Array Research Articles

Sputter Deposited, Electrically Conductive, Oxidation Resistant Coatings

ABSTRACTSignificant polymer weight loss has been observed due to environmental ashing by atomic oxygen at low earth orbital (LEO) altitudes. Static charging during deployment and charging caused by the space plasma in LEO polar orbits may cause electromagnetic interference (EMI) problems on insulating polymer materials that are integral to such applications as high voltage solar arrays. Simultaneous ion beam sputter deposited coatings of indium-tin-oxide (ITO) with polytetrafluoroethylene (PTFE), carbon, air, or methane were investigated as potential solutions to these problems. The purpose of this research was to improve the flexibility of ITO coatings with these additives and to study the effect the addition of these materials had not only on the flexibility of ITO sputter deposited thin films but also on the conductivity and optical properties.

The Effect of Solar Array Voltage Patterns on Plasma Power Losses

The use of high-voltage solar arrays in space is discussed in connection with the draining of array power by currents flowing between exposed surfaces through the surrounding plasma. The possibility of reducing the power loss by arranging solar cell strings in repeated small-area modules to eliminate any large areas at high potentials is investigated. It is found that the difference in power loss between modular and linear patterned high-voltage arrays is fairly small. Although the use of modular patterns can reduce the effective mean potential by about 10%, for the type of configuration being considered there is also a 10% increase in sheath area, leading to only a few percent change in total power loss. It is concluded that plasma power loss should not be a primary consideration in designing the physical arrangement of high-voltage arrays.

Spacecraft-Generated Plasma Interaction with High-Voltage Solar Array

Calculations are made of the effect of interactions of spacecraft-generated plasmas and high voltage solar array components on an advanced Solar Electric Propulsion system. The plasma consists of mercury ions and electrons resulting from the operation of ion thrusters and associated hollow cathode neutralizers. Because large areas of the solar array are at high potential and not completely insulated from the surrounding plasma, the array can, under some conditions, collect excessive electron currents. Results are given for the parasitic currents collected by the solar arrays and means for reducing these currents are considered.

High-Voltage Solar Array Technology

REVIOUS high-voltage solar array (HVSA) studies conducted17 under the sponsorship of NASA-LeRC have all come to similar conclusions with regard to the relative power system performance gains possible with the HVSA, the generalized techniques for implementation, the specific problem areas associated with device requirements, and the analytic evaluation of HVSA operation in the space environment. This paper considers forms most practical for ion propulsion and high-power communication satellite applications. Attention is focused on defining the concepts for total power systems in greater detail, on breadboard implementation and testing of critical subsystems associated with the total system approach, and on studies to increase the understanding of solar array/ space plasma interactions so that the selection of array materials and physical designs can be based on a knowledge of the requirements and penalties involved.

Feasibility of High Voltage Solar Arrays

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.