CHARACTERISTICS OF SOLAR WIND NEAR ORBIT OF JUPITER

It is assumed that the solar wind flow out to at least 5·2 A.U. is adiabatic, with no change in streaming speed, and near Earth observations are extrapolated to determine the plasma characteristics in the distant interplanetary medium. We show that at the orbit of Jupiter, electron plasma oscillations and electron whistlers have distinct and novel characteristics; the high frequency electromagnetic waves will be unstable in the wind if T||(-) < T(-), and the wind flow will be supersonic with respect to electron plasma oscillations when the electrons are sufficiently cool. Both of these conditions arise if the expansion is strictly adiabatic. Near Jupiter, the large gravitational field can distort the particle distribution functions well beyond the conventional shock boundary, and we conjecture that a low frequency drift instability associated with ion sound waves may also be significant in the upstream solar wind. © 1969.