Temperature anisotropy instabilities; combining plasma and magnetic field data at different distances from the Sun.

摘要

We present a new data analysis method enabling the observation of magnetic field fluctuations associated with temperature anisotropy instabilities using the Ulysses spacecraft. The movement of the spacecraft away from the Sun causes the observed plasma conditions, turbulent fluctuation amplitude, magnetic field strength and important physical scales to change. We normalize wavelet power spectra of the magnetic field using local values for the proton gyroscale and large scale magnetic field fluctuation amplitude to remove the effects of varying heliocentric distance.We recover the enhancement of magnetic fluctuations where temperature anisotropy instability growth rates are large, as seen by previous studies in the ecliptic at 1 AU. This method can be applied to any spacecraft data that contains large changes in physical scales, magnetic field strength or other plasma parameters, for example the upcoming Solar Orbiter and Solar Probe Plus missions.