Measurement of plasma drifts in space and laboratory plasmas by the resonance cone technique

The radiation field of a small antenna immersed i a magnetized plasma is, for certain frequency bands, resonantly enhanced on the ''resonance cone'' (r.c.), which is aligned with the magnetic field, and whose apex is at the transmitting antenna. It is well known that, in a warm plasma, electron density and temperature can be deduced from the r.c. maximum angle and from an associated interference pattern. Because the maximum angle depends on the frequency, one expects an immediate influence of the Doppler effect ω'=ω-k·vd. In the case of a field aligned electron drift, the r.c. pattern is apparently convected downstream, which leads to an upstream-downstream asymmetry of the cone-angle, whereas cross-field drifts bend the r.c. sidewards. Since this asymmetry is easily detectable, it was proposed to use this asymmetry as a diagnostic technique for measuring the electron drift velocity. However, the cited theoretical approaches result in different functional dependences as well as different coefficients for deducing the drift velocity from the measured asymmetry. Moreover, up to now only the case of field aligned drift has been treated rigorously. For exactly perpendicular drift, a cold-plasma approximation is available. For arbitrary drift orientation, we had suggested recently to use an interpolation formula, which reduces to the kinetic theory result for field-aligned drift, and uses the cold-plasma coefficients for the angular dependence. In this contribution we present experimental observations from the r.c. instrument ''COREX-1'', which investigated plasma parameters and field aligned drifts in the mid-latitude ionosphere. In addition, laboratory results are presented for a critical comparison of field-aligned drifts with the competing models. (author) 11 refs., 5 figs