Physical Mechanism of the Lower-Hybrid-Drift Instability in a Collisional Plasma.
NAVAL RESEARCH LAB WASHINGTON DC
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During the past several years, high-frequency radar backscatter experiments have revealed a spectrum of short-wavelength i.e., below the ion gyroradius irregularities during equatorial spread F ESF. Radar backscatter observations at 50 MHz, 155 MHz and 415 MHz indicate density fluctuations exist with scale sizes of 3m, 1m, and 36 cm, respectively FARLEY et al., 1970 WOODMAN and LAHOZ, 1976 COSTA and KELLEY, 1978a,b HUBA et al., 1978. Most recently, TSUNODA 1980 has observed radar backscatter from 11 cm 1320 MHz irregularities during equatorial spread F at high altitudes, using the TRADEX radar. These observations were part of a coordinated Defense Nuclear Agency campaign at Kwajalein to study ionospheric irregularities during equatiorial spread F. Sharp density gradients were observed during this campaign M. C. KELLEY, private communication, 1980 and have been observed during past equatiorial spread F events COSTA and KELLEY, 1978a,b. The scale lengths of these gradients range from tens of meters to several hundred meters and are presumably due to primary longer wavelength instabilities such as the Rayleigh-Taylor instability. Based upon the above evidence, it has been suggested that various drift instabilities are responsible for the short wavelength irregularities HUBA et al., 1978 COSTA and KELLEY, 1978a,b HUBA and OSSAKOW, 1978a,b, depending upon the wavelength observed.
- Atmospheric Physics
- Active and Passive Radar Detection and Equipment
- Plasma Physics and Magnetohydrodynamics