Characteristics of the sheath resonance (SHR) observed by the impedance probe are discussed. Two phenomena about SHR on the fSHR-fP diagram have been observed at the sounding rocket experiment of S-310-18,launched at 11 : 00 JST on January 26,1988. Those are as follows : first, at the lower E region, a frequency at SHR (fSHR) increases slightly, the Q value of SHR decreases, and the equivalent probe-capacitance at the low frequency (CL) increases slightly. The ratio of the sheath thickness (S) to the local debye length (S/λ_D) has changed from 1.0 to 1.5 at about 75 second after launch when the height is about 100km.; second, at the higher region, the CL value which is interpreted to be equal to the equivalent ion sheath capacitance around the probe (CS) decreases with the simultaneous increasing of the fSHR frequency. The S/λ_D value has changed from 1.5 to 1.75 at about 140 second, at 170km. The CL value has decreased gradually and the fSHR frequency increased discontinuously. Above observed results in the first case at about 75 second are explained by taking into account of an effect of collision frequency (ƒ_ν) and adequately explained by using an unique modified sheath model which has a different physical structure. The second variation at about 140 second is sufficiently interpreted to be due to the negative bias effect at the probe potential.
電離層プラズマ中で観測された SHR 共鳴の特性 : E 層総合観測実験のインピーダンスプローブ特性
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