Quasi-thermal noise spectra measured by a dipole antenna in the upper hybrid frequency band

Quasi-thermal noise (QTN) spectroscopy is one of the most effective tools f or in situ diagnostics in space plasmas (Meyer-Vernet et al., 1998; Meyer-V ernet and Perche, 1989; Chugunov and Trakhtengerts, 1978). This method prod uces routine measurements of the bulk electron density and temperature; rec ently it has been extended to measure the ion bulk speed. Among the advanta ges of the method its immunity to spacecraft potential and photoelectron pe rturbations should be noted. Quasi-thermal noise spectroscopy is used parti cularly on Ulysses and Wind. However for the interpretation of QTN data the calculation of the noise voltage induced on antennas under different condi tions is necessary. This question is especially complicated and so far insu fficiently studied in magnetized plasmas. In the present paper we calculate the spectrum of the noise voltage induced on a dipole antenna in the upper hybrid frequency range. The computations are adapted to the interpretation of data acquired on the Ulysses and Wind spacecraft.