He++ behavior on the an interplanetary shock wave

In our study we analyzing the fine structure of interplanetary shock wave fronts recorded by the BMSW experiment, installed onboard the SPEKTR-R satellite. The high time resolution of the spectrometer (0.031 s for the plasma flux magnitude and direction and 1.5 s for velocity, temperature, and density) makes it possible to study the internal structure of the IPs front.

BMSW experiment registered 55 IPs waves from 2011 to 2019. For 21 events (where the temperature was not very high), the parameters of twice-ionized helium (He++ or α-particles) - density (absolute value and relative to protons content in the solar wind plasma), velocity, temperature. It is shown that the speed of He++ is slightly less (for about 5%) than the speed of protons, the relative density of He++ rarely exceeds 10%, and the temperature of He++ is about 2 times higher than the temperature of protons.

On the IPs front, short-term and significant (up to 20%) jumps in the relative density of He++ were detected in several events. No dependence was found between Mms/proton beta and He++ density changing after IPs front. However, we detected that the lower Qbn parameter is, the more the relative density of He++ falls behind the IPs front.