Variations of He++ Ion Parameters at Interplanetary and Earth’s Bow Shock Fronts

• Published in: Geomagnetism and Aeronomy 2022-10, Vol.62 (5), p.505-513
• Main Authors: Sapunova, O. V., Borodkova, N. L., Zastenker, G. N., Yermolaev, Yu. I.
• Format: Article
• Language: English
• Subjects: Collisionless plasmas; Density; Earth and Environmental Science; Earth Sciences; Geophysics/Geodesy; Helium; Helium ions; Ions; Magnetic fields; Mathematical analysis; Parameters; Protons; Shock fronts; Solar wind; Specific gravity
• ISSN: 0016-7932; 1555-645X; 0016-7940
• DOI: 10.1134/S0016793222050103

— This article investigates variations in the parameters of the twice ionized helium ions He ++ (α-particles) of the solar wind plasma when crossing shock fronts in collisionless plasma, that is, interplanetary (IP) shocks and the Earth’s bow shock. Data from measurements of the BMSW instrument mounted on the SPEKTR-R satellite are used. Using data from this instrument, the parameters of protons and α-particles in the solar wind (velocity, temperature, density, magnitude and direction of the flux, and the relative density of He ++ ions) are calculated. It is shown that the absolute density of He ++ ions increases behind the shock front (of both the IP and the bow shock), while the relative density of He ++ ions decreases behind the IP front and increases behind the bow shock front. A correlation between the change in the relative density of He ++ ions and the value of the angle between the magnetic field and shock normal direction f θ Bn is obtained: the higher the value of θ Bn is, the larger the value of the relative density of He ++ ions is behind the shock front.