Spectra of Fluctuations of Solar Wind Plasma Parameters near a Shock Wave

The paper investigates the characteristics of the power spectra of fluctuations in the density of protons and α particles near the front of the interplanetary (IP) and Earth’s bow shock (BS). The frequencies of the power spectra break of fluctuations in the density of protons and α particles were calculated before and behind the ramp of the Earth’s bow shock and interplanetary shock. For the disturbed solar wind beyond the IP ramp, the frequency of the spectrum break of proton fluctuations turned out to be noticeably higher (on average 1.3 Hz) than in the undisturbed region (∼0.8–1.0 Hz), which is explained by an increase in both the velocity and the density of particles. In the case of α particles, the frequency of the spectrum break of fluctuations behind the IP front also increased by almost two times (from 0.7 to 0.12 Hz). It is shown that the average value of the frequency of the proton spectra break behind the ramps is less (0.6 Hz) than in the solar wind (1.0 Hz), due to lower velocity. For α particles, this effect was not statistically detected due to an increase in the density (0.11 Hz for both regions) in the case of BS.