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21.
Fourier transform techniques were used to analyse a time series of experimental data in order to isolate a repeatedly scanned component, periodic and non-periodic temporal components and noise. The method was applied to a rocket-home electrostatic electron energy analyser being swept at a fixed rate, but having the spectra modified by non-periodic temporal variations and modulation at the spin rate of the rocket. It was found that by suitable displacement of the data amplitude origin and shaping of the ends of the time series, a very good separation of the various components was obtained. This indicates that the technique is a method particularly applicable to analysing data in which different periodic components are present. 相似文献
22.
This paper presents an analysis of interactions between the space shuttle Orbiter and the ionosphere based on thermal plasma data obtained from a Spherical Retarding Potential Analyzer (SRPA) and a Langmuir Probe (LP) flown on the third Space Shuttle flight (STS-3) in March 1982. While previous work on spacecraft-plasma interactions has dealt with wake effects, the present work deals with effects that are seen in ram conditions that have not been previously discussed. One observation is a higher degree of plasma turbulence than has been reported from unmanned spacecraft measurements that manifests itself as a frequency component at 2.2 kHz in the SRPA signal. We also see unusually high number densities of what appear to be ions with a mass of at least 30 or 32 amu and a temperature in the range 2000–3000 K. Coincident with the enhanced molecular ion species we see the temperature of the thermal electrons elevated to above 5000 K. It is hypothesized that these measurements are evidence for a plasma instability resulting from the motion of the outgassing Orbiter through the ionosphere. 相似文献