Physics of auroral phenomena : proceedings of the 39th annual seminar, Apatity, 29 February-4 March, 2016 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2016. - 167 с. : ил., табл.

"Physics o f Auroral Phenomena", Proc. XXXIX Annual Sem inar, A patity, pp. 70-73, 2 0 1 6 © Polar Geophysical Institute, 2016 Polar Geophysical Institute FINE STRUCTURE OF THE INTERPLANETARY SHOCKS OBSERVED BY BMSW EXPERIMENT ONBOARD THE SPEKTR-R 0 .V . Sapunova, N .L . Borodkova, G .N . Zastenker Space Research Institute o f the Russian Academ y o f Sciences e-mails: sapunova_olga@mail.ru, nIbor@mail.ru, gzastenk@iki.rssi.ru Abstract. Interplanetary (IP) shocks are one of the main factors influencing the space weather. The fine structure of the front of collisionless shock has been investigated for planetary shocks from magnetic field measurements whereas IP shocks are less often studied. BMSW [1] plasma spectrometer onboard the SPEKTR-R satellite, launched in 2011, measures the ion moments with high-time resolution - 0.031 s and it allowed us to study ramp region of the IP shocks using ion moments, which were completed by magnetic field measurements from ACE, WIND, THEMIS and CLUSTER spacecraft. All registered IP shocks were studied and their main characteristics were calculated: p (the ratio of the solar wind thermal to the magnetic pressure), 0Bn (the angle between the upstream magnetic field and shock normal direction), Mms (Magnetosonic Mach number - the ratio of the IP velocity to the propagation speed of magnetosonic waves), IP shock velocity. The study shows that the ramp thickness defined from plasma measurements roughly corresponds to the ramp thickness derived from the magnetic field measurements and lies within interval from 40 to 600 km. In some cases the precursor waves were observed in the front of subcritical shocks both in plasma and magnetic measurements. It was found that their wavelengths varied from 70 to 400 km. 1. Introduction Interplanetary shock waves which are generated by solar flares and the emission of coronal material are one of the major sources of perturbation in the solar wind [2, 3, 4]. On the front of a shock wave there are a redistribution of energy of directed plasma motion into thermal energy, and the acceleration of the part of particles to significant energies that leads to a large growth of all kinetic parameters of plasma and magnetic field of solar wind. The most important parameters that characterize the shock wave structure are: the parameter p (ratio of thermal pressure to magnetic pressure), the angle 0Bn (angle between the normal to the wave front and the direction of magnetic field in the unperturbed solar wind), magnetosonic Mach number [5,6]: where Pmag- magnetic pressure, Pt- thermal pressure, V1P- shock wave front speed, Cms- magnetosonic speed, Ca- Alven speed, Cs - sound speed The shock front is a thin transition layer (or ramp) from the unperturbed to the perturbed solar wind. Many works were devoted to study the thickness of the wave front according to magnetic measurements [7, 8, 9, 10] with high time resolution. The thickness of the wave front according to plasma measurements was investigated in [11] and depends to excessively steep spatial gradients, and their steepening is determined by the interaction between nonlinear processes of dispersion and dissipation. The definition of the characteristic scale o f the shock front is an important task, because it allows us to determine the dominant processes in the interaction mechanism and its characteristics 2. Experimental data For research we used measurements of the plasma spectrometer BMSW (Fast Monitor of Solar Wind) installed on the SPEKTR-R satellite with a time resolution 3 s for the velocity, temperature and concentration, and 0.031 s for the ion flux (magnitude and two angles). According to the BMSW device measurement it was identified interplanetary shock waves registered by the device from August 2011 to March 2016. The BMSW data was complemented by magnetic and plasma measurements at other satellites, which were in the solar wind at the same time with the highest possible time resolution. We usually used data from following satellite devices: 70