Dynamics of the Dissipation Range for Solar Wind Magnetic Fluctuations

Robert J. Leamon, Norman F. Ness, Charles W. Smith and Hung K. Wong

Proceedings, Ninth International Solar Wind Conference (Nantucket, MA), 469-472, AIP, New York (1999)

Abstract:

The dissipation range of interplanetary magnetic field (IMF) fluctuations is perhaps the least-studied aspect of the IMF. This is undoubtedly due, at least in part, to the large volume of data required to perform thorough studies of the high-frequency spectrum. We examine the properties of the dissipation range at 1 AU as observed by the WIND spacecraft, which include:
(1) a general steepening of the power spectrum at spacecraft-frame frequencies comparable to, but greater than, the proton cyclotron frequency;
(2) magnetic fluctuations that are largely transverse to the mean magnetic field, but less transverse than is seen in the high-frequency extent of the inertial range;
(3) significant, but not maximal helicity and polarization signatures that indicate that ion-resonant dissipation is contributing to the magnetic spectrum;
(4) a dominant fraction of the total magnetic energy is associated with wavevectors at large angles to the mean magnetic field; and
(5) strong plasma beta effects in the above results.
In addition, we present a comparison of the observed onset of dissipation with a theory based on Kinetic Alfvén waves.