Space Experiments Aboard Rockets: SPEAR III
Morris, James H.
Olsen, Richard Christopher
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The SPEAR III experiment was conducted in an effort to better understand and compensate for the effects of satellite charging, at levels up to KV. This experiment was designed as a lower-ionosphere test to both record vehicle charging and the effect of neutral-gas grounding systems. Prelaunch tests were conducted at the NASA-Plum Brook facility; launch took place at the NASA-Wallops facility. Electrostatic analyzer data provided a record of the rocket body potential, and indications of ion production, or energy-angle scattering within the plasma sheath. Plasma wave information was extracted from floating probe data and skin current probe data. Both provided sampling to resolve signals up to 10 KHz; the skin current probe also provided burst-mode sampling up to 500 MHz. There were no obvious signals in the 0-10 KHz data, other than a diffuse, low-frequency noise. The burst-mode data, acquired at the initiation of each 5-second charging sequence, showed a strong signal at around 100 KHz. This roughly corresponds to the lower-hybrid resonance frequency. It is possible, that LHR waves are responsible for energy-angle scattering of the ion flux accelerated to the charged rocket body
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