Abstract Title: *
Quasi-thermal noise in anisotropic plasmas

Authors: *
M. M. Martinović, A. Zaslavsky, M. Maksimović

Institution: *
University of Belgrade, Faculty of Mathematics

Preferred format: *
poster presentation

Abstract Text: *
Quasi-thermal noise (QTN) spectroscopy enables precise determination of plasma density and
temperature by analyzing the spectrum of voltage fluctuations measured at the terminals of an
antenna embedded in the plasma. This technique has been routinely used in space plasmas,
especially in the solar wind, for four decades. Throughout this period, as in situ measurements
have been available only at distance from the Sun comparable to 1AU, the method assumed the
solar wind plasma to be isotropic as a justified approximation. However, at solar distances
<0.3AU, the plasma anisotropy is expected to significantly affect the measurements. In this work
we introduce, for the first time, the QTN models for anisotropic plasma, along with simulations of
the future Solar Orbiter and Solar Probe Plus measurements. We conclude that presence of the
anisotropic component, usually labels as “the strahl”, is expected to be considerable close to the
so called plasma peak, which appears in the vicinity of the plasma frequency. In this region, the
signal is significantly increased.