On February 8, 1992, Ulysses traversed the magnetosphere of Jupiter. That
spacecraft carried the Unified Radio and Plasma Wave (URAP) experiment
[Stone et al., 1992a], including a low-frequency
receiver which was connected to a 2x35 m wire dipole antenna and swept the
frequency range 1.25 to 48.5 kHz in 128 s through 64 equally spaced frequency
channels of 0.75 kHz bandwidth. The URAP spectra show weakly banded emissions
between consecutive gyroharmonic frequencies. These observations were interpreted
by [Meyer-Vernet, Hoang and Moncuquet, 1993] as quasi-thermal noise (QTN) in
Bernstein waves [Sentman, 1982].
This interpretation was confirmed by [Moncuquet, Meyer-Vernet and Hoang, 1995], who derived from the spectra acquired in the Io plasma torus
( 
to 
) a number of dispersion curves in very good agreement
with the theoretical dispersion characteristics of Bernstein modes in a stable
plasma, from which the electron temperature was derived.
Here we shall focus on the spectra acquired between and
on a quasi-radial spacecraft trajectory at 
from the
centrifugal equator. The magnetic field was decreasing as the Ulysses
distance R to Jupiter increased [Balogh et al., 1992], so
that each spectrum contains several (3 to 10) gyroharmonic bands. As R
increased, the plasma frequency 
decreased, bringing inside our spectral
range some features linked to the Q resonances (hereinafter noted 
)
predicted by Bernstein dispersion theory in each intraharmonic band above
.
In section 2, we briefly review the theory of the resonances. In
section 3, we show how these resonances and the absence of Bernstein waves
propagation at higher frequencies result in an abrupt drop of the voltage power
spectrum. These features are used in section 4 to measure the and
deduce . We finally compare in section 5 the resonance frequencies
determined here with those measured by the Ulysses relaxation sounder
experiment.