Vacuum Arcs on Solar Array Surfaces

What is it about?

Arcs on the solar arrays appear to be the most plausible source for the electromagnetic radiation observed with the Arecibo radio telescope. In the laboratory, electrostatic discharges (arcs) on solar array coupons were studied in a simulated GEO environment. Arc current pulses were recorded with a high time resolution - up to 0.2 ns. Spectral properties of these pulses demonstrated no monotonic behavior but rather separated peaks within the frequency range of 100-1000 MHz. Electromagnetic radiation from these arcs was registered and recorded with a Yagi antenna 8 m distant from the arc site, and a high-speed oscilloscope. analysis of the spectra resulted in the discovery of well separated “lines”. Evaluation of arc current spectra and radio frequency spectra revealed statistically significant patterns in the frequency domain. Measured radio fluxes and theoretical estimates of the power of electromagnetic radiation from arcs on spacecraft solar arrays strongly argue in favor of the arcing hypothesis for the source of this radiation. These results have enabled considerable progress to be made in understanding the physical nature of the generation of electromagnetic radiation by transient vacuum discharges.

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