Ec. Sittler et Lf. Burlaga, ELECTRON TEMPERATURES WITHIN MAGNETIC CLOUDS BETWEEN 2 AND 4 AU - VOYAGER 2 OBSERVATIONS, J GEO R-S P, 103(A8), 1998, pp. 17447-17454
We have performed an analysis of Voyager 2 plasma electron observation
s within magnetic clouds between 2 and 4 AU identified by Burlaga ann
Behannon [1982]. The analysis has been confined to three of the magnet
ic clouds identified by Burlaga and Behannon that had high-quality dat
a. The general properties of the plasma electrons within a magnetic cl
oud are that (1) the moment electron temperature anticorrelates with t
he electron density within the cloud, (2) the ratio T-e/T-p tends to b
e >1, and (3) on average, T-e/T-p approximate to 7.0. All three result
s are consistent with previous electron observations within magnetic c
louds. Detailed analyses of the core and halo populations within the m
agnetic clouds show no evidence of either an anticorrelation between t
he core temperature T-C and the electron density N-e or an anticorrela
tion between the halo temperature T-H and the electron density. Within
the magnetic clouds the halo component can contribute more than 50% o
f the electron pressure. The anticorrelation of T-e relative to N-e ca
n be traced to the density of the halo component relative to the densi
ty of the core component. The core electrons dominate the electron den
sity. When the density goes up, the halo electrons contribute less to
the electron pressure, so we get a lower T-e. When the electron densit
y goes down, the halo electrons contribute more to the electron pressu
re, and T-e goes up. We find a relation between the electron pressure
and density of the form P-e = alpha N-e(gamma) with gamma approximate
to 0.5.