Electron-beam irradiation effects on silica glass studied by cathodoluminescence for solar battery of spacecraft
- Paper number
IAC-06-E2.1.03
- Author
Mr. Takuya Harada, Shibaura Institute of Technology, Japan
- Coauthor
Dr. Hiroyuki Nishikawa, Shibaura Institute of Technology, Japan
- Year
2006
- Abstract
Electrostatic discharges in the solar panels on geosynchronous spacecrafts are a suspected cause of their anomalous operation. The accidents involving the electrostatic discharge in the space environment must be deeply related with an interaction between dielectric materials and high-energy particles. The high energy particles include electrons and protons abundant in the space environment, which are produced by unexpected solar flares. However, the detailed mechanism of the damage on the solar panels by the incident high-energy particles has not been well understood. Solar battery array comprises of the cover glass which is a typical insulator, inter connector which is conductor, and solar battery which is semiconductor. Since the inter-connector is exposed to the outer space, the inter connector is expected to be negatively biased against the plasma, while the cover glass keeps almost the same potential. Therefore, electric discharge can occur at the triple junction of the plasma, cover glass, and inter connector by a localized high electric field. The purpose of this study is to evaluate irradiation effects on silica glass in-situ by a keV-order electron beam through the measurements of CL spectra by measuring the time response of the CL for various types of silica glass with different concentrations of impurities. Defects in silica glass have been studied by mainly optical measurements. Among these, CL technique has a capability in detecting luminescence centers localized in the region less than micrometer scale using an electron microprobe focused down to several tens to few nanometers. In this study, we studied the irradiation effects of silica under keV-electron beam, where excitation was possible across the band gap of silica around 8 eV. Therefore, the CL technique is suitable for the study of defect generation and excitation of defects in wide-gap materials such as silica. We observed luminescence bands due to the oxygen deficient centers (ODCs) at 290 nm and 460 nm and the nonbridging oxygen hole centers (NBOHCs) in silica glass at 650 nm by the CL measurements. The time response of the CL comprises increase and decay components, where the generation and annihilation of defects such as the ODCs and the NBOHCs are affected by the presence of impurities.
- Abstract document
- Manuscript document
IAC-06-E2.1.03.pdf (🔒 authorized access only).
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