High Power Needs for Commercial Satellites
This overview paper presents estimates of the photovoltaic power systems needed on commercial communications spacecraft in the year 2000. These are developed in the form of power requirements based on extrapolation of the historical growth in communications traffic and are about 5 to 15 kW. The paper also addresses the key technology drivers in these photovoltaic systems. The importance of reducing mass in the power system is described in terms of the tradeoff with communications systems mass to maximize communications revenue. It surveys solar array components and subsystems to meet these future requirements and attempts to identify the development candidates with a large payoff potential and a high probability of successful development.
Development of AlGaAs/GaAs solar cells with space qualifications
The AlGaAs/GaAs solar cells with higher performances of radiation resistance and energy conversion efficiency than those of usual silicon solar cells have been developed. The test results of the evaluation for these solar cells with space specifications are presented. 2 cm X 2 cm AlGaAs/GaAs solar cells with efficiencies in the range of 16.4% to 18.6% (typical 17.5%) at Air Mass Zero (AM0) (135.3 mW/cm/sup 2/ illumination and at 28/sup 0/ C) have been evaluated in the following tests; (1) Thermal shock, (2) Pull test, (3) Humidity, (4) Storage at high temperature in vacuum, (5) Ultraviolet irradiation, (6) Radiation resistance (electron, high energy proton, low energy ploton and gamma ray), (7) Coupon test ( operation life, vibration, shock and thermal shock). The results indicated that the AlGaAs/GaAs solar cells have high quality and performance in space use.
EPR of a carbon‐oxygen‐divacancy complex in irradiated silicon
Additional EPR experiments on the Si-G15 spectrum, previously observed in p-type, pulled silicon after electron irradiation, are described. The hyperfine interaction with the 29Si nuclei and the quenched-in defect alignment under uniaxial stress are newly observed. A correlation is made between the G15 spectrum and the C(3) infrared absorption band at λ = 11.6 μm via the defect symmetry, stress response and their dependence on irradiation temperature and electron-fluence. Based on the new experimental results as well as existing results from the infrared and EPR studies, the G15 spectrum is identified as arising from a positive charge state of a defect which may be viewed as a carbon-oxygen molecule bonded within a divacancy. The trapping of a mobile interstitial carbon by a [vacancy ± oxygen] pair results in the formation of the [CO ± V2] complex and the liberation of a selfinterstitial at room temperature. The electrical level of G15 is determined to be (Ev ± 0.32) eV. Tentatively the G16 spectrum is identified as being due to the negative charge state of this defect and having an electrical level at (Ec — 0.43) eV. 
 
 
 
Es werden weitere EPR-Experimente am Si-G15-Spektrum durchgefuhrt, das fruher schon an nach dem Czochralski-Verfahren hergestelltem, p-leitendem Silizium nach Elektronenbestrahlung beobachtet wurde. Die Hyperfeinwechselwirkung mit 29Si-Kernen und die Ausrichtung der durch Abschrecken eingefrorenen Fehlstellen unter axialer Spannung werden erneut beobachtet. Uber die Symmetrie der Fehlstelle, die Reaktion auf Spannung und deren Abhangigkeit von der Bestrah-lungstemperatur und der Elektronendosis wird das G15 Spektrum mit der C(3)-Infrarot-Absorptionsbande bei λ = 11,6 μm korreliert. Mit diesen neuen experimentellen Ergebnissen und den schon bestehenden Ergebnissen von Infrarot- und EPR-Untersuchungen wird angenommen, das das G15-Spektrum von einem positiv geladenen Zustand einer Fehlstelle kommt, die man als ein in einer Doppel-Leerstelle gebundenes CO-Molekul ansehen kann. Ein bewegliches Kohlenstoff-Zwischengitteratom wird von einem (Leerstelle ± Sauerstoffatom)-Paar eingefangen; das ergibt den [CO ± V2] Komplex, wahrend eine Eigen-Zwischengitterfehlstelle gebildet wird. Das Energie-niveau von G15 wird zu (Ev ± 0,32) eV bestimmt. Auserdem wird vermutet, das das G16-Spektrum von einem negativ geladenen Zustand dieser Fehlstelle stammt und ein Energieniveau von (Ec — 0,43) eV hat.