Further analysis of non-linear density fluctuations in the foot of quasi-perpendicular shock

Abstract

Dissipation processes and shock structure in the strong quasi-perpendicular case are mainly controlled by reflection of part of the ions from the shock front. The reflected beam excites strong electric field and number density fluctuations within the foot. However no significant heating of ions is observed until the transition to downstream state occurs on a very short scale within magnetic ramp. These processes are analyzed with the measurements of ion flux and electric field turbulence measured on Prognoz 8 and Prognoz 10 — Intershock satellites. Saturated lower-hybrid-range turbulence in the foot leads to the development of very strong ( Δ N N ∼ 1 ) number density fluctuations. These structures are accompanied by electric field fluctuations of ∼ 10 mV/m and by ion-sound bursts. The measured electric potential profile in the non-linear structure is very close to the number density variation profile suggesting an electrostatic nature of turbulence. A comparison of the electric field variation with the ion flow vector velocity allows one to estimate the magnitude of the electric potential variation across this structure and its linear scale.