ASPI experiment: measurements of fields and waves on board the INTERBALL-1 spacecraft

Abstract

Abstract. The plasma-wave experiment ASPI (analysis of spectra of plasma waves and instabilities) on board the INTERBALL spacecraft is a combined wave diagnostics experiment. It performs measurements of the DC and AC magnetic ®eld vector by¯ux-gate and searchcoil sensors, the DC and AC electric ®eld vector by Langmuir double probes and the plasma current by Langmuir split probe. Preliminary data analysis shows the low noise levels of the sensors and the compatibility of new data with the results of previous missions. During several months of in-orbit operation a rich collection of data was acquired, examples of which at the magnetopause and plasma sheet are presented in second part of the paper. Scienti®c objectivesThe INTERBALL project is orientated towards the investigation of the interaction between di erent parts of the magnetosphere in relation to changes in the solar wind and ionosphere. First INTERBALL-1 orbits passed through the solar wind, bow shock, magnetosheath and magnetopause regions. Several months later the orbit apogee shifted to the near-Earth magnetotail, so that INTERBALL-1 observed the tail lobes and the plasma sheet. These orbit parameters allow the neutral sheet region to be studied for several hours.Plasma waves and¯uctuations play a crucial role in the highly collisionless space plasma. Waves and¯uctu-ations are of particular importance at the plasma boundaries such as bow shock, magnetopause, neutral sheet, and plasma sheet boundary layer. Wave-particle, interactions in the plasma result in processes like: (1) anomalous transport (pitch-angle and spatial di usion, conductivity, viscosity); (2) energy redistribution and plasma heating; (3) generation of anisotropic distribution functions and their relaxation; (4) triggering of large-scale instabilities.The speci®c objectives of the ASPI wave and ®eld experiment on board INTERBALL-1 are:1. The study of the¯uctuation characteristics in di erent regions of the magnetosphere and the use of these data as high-time-resolution indicators of plasma phenomena. 2. The determination of the micro-scale plasma characteristics (e.g. di usion and anomalous transport coe cients, wave-wave and wave-particle coupling).

Ion resonance acceleration by dipolarization fronts: analytic theory and spacecraft observation

“…Magnetic field data from the ASPI/MIF-M experiment (Klimov et al, 1997) and low energy (<24 keV) ion moments from the CORALL experiment (Yermolaev et al, 1997) are analysed to reveal DFs. High energy particles in the range 20-800 keV are measured with DOK-2 experiment (Lutsenko et al, 1998).…”

Spatial variation of eddy-diffusion coefficients in the turbulent plasma sheet during substorms

“…The satellite spin axes was oriented along the X-direction of the GSM coordinate system, hence the ion bulk velocities were obtained in Y-and Z-directions only. We also used 2 min averaged geomagnetic field data, obtained by a digital fluxgate magnetometer MIF-M/PRAM (Klimov et al, 1997). Only the events that satisfied the following criteria were selected for analysis: number density 0.1-10 cm −3 , ion temperature T ≥0.3 keV, and average bulk velocity ≤100 km/s.…”

Interball-tail observations of vertical plasma motions in the magnetotail

“…The magnetic field on board IT was measured by the ASPI/MIF-M instrument (Klimov et al, 1997), and in this study we used the 2-min averaged data. IMF and solar wind (SWE) data measured by Wind spacecraft were taken from the CDAWeb public database and shifted by convection time necessary for the solar wind to cover the distance between Wind and IT.…”