Authors: Savov, E.P., P.I.Nenovski, I.I.Bogomilov, L.I.Simeonov
Reference: Comp.Rend.Acad.bulg.Sci., 43,76, 41-44, 1990
Space projects carried out in the past revealed that plasma in the Solar System has cellular structure with thin boundary layers separating plasma regions of widely different characteristics. The data from the measurements of the charged particle distribution functions and composition are of fundamental importance for understanding the occurring plasma processes. These data elucidate the movements and instabilities of the various magnetospheric boundary layers and the related coupling mechanisms. Certain magnetopause characteristics are inferred from the three dimensional particle distributions. The past history of some plasma populations can be revealed by the character of the ion distributions. The measurements of the 3D ion distributions and composition are indispensable for mapping the connections between the different space plasma regimes and for studying of their interactions. This work presents a sensor for simultaneous measurement of the 3D ion and electron distributions. It consists of two collimators and two geometrically similar nearly quadrispherical electrostatic devices of ?top hat? type with symmetrical optics to ensure uniform velocity space coverage. The M/Q ratio can be varied by four cross-field velocity analyzers, occupying four 22.5º sectors. Conditions for free pass of the ions are secured in adjacent sectors. The ions are accelerated to 20 KeV/Q. The ions and the accelerated electrons are detected on different chevron microchannel plates and discrete collectors.