Publication at Faculty of Mathematics and Physics |
2014
Abstract
Wave packets are frequently observed upstream and/or downstream of shocks in a magnetized plasma. We present a comparison of Wind and Spektr-R observations of 27 interplanetary low-Mach number (<5.5) shocks that reveals that (1) the wavelengths of both upstream and downstream waves conserve over the spacecraft separation, (2) in the frequency range of 0.5-5 Hz, their wavelengths are directly proportional to the shock ramp thickness that is controlled by the ion thermal gyroradius, and (3) the phase shift between density and temperature variations within downstream wave packets is about 90 degrees.
These results emphasize a role of kinetic processes in the formation of low-Mach number shocks.