The name of the project APEX is a reduction from words " Active Plasma Experiments " . The core of the project are active experiments with injection of electron and (or) plasma beams from a board of the satellite with simultaneous registration of the phenomena, produced by interaction of injected beam with background plasma.

Essentially important peculiarity of the project are synchronous measurements of the basic physical parameters of the environment,of the beam and generated fields on two space separated vehicles - main satellite APEX and subsatellite MAGION-3 . An independent subsatellite with adjusting truster installation allows to carry out simultaneously measurements on various mutual distances (from 0,01 up to 1000-2000 km), at different areas of disturbed environment and propagation of a beam, at different zones of a magnetosphere and ionosphere. The speed and distance of separation both spacecrafts are controlled by small neutral gas trusters on the MAGION-3. The "boomerang" maneuvers of MAGION-3 were performed few times: it was pushed forward and returns backward to main satellite , so MAGION-3 escaped from the main APEX up to few hundreds km and came back at distance about 0,4 km.

The important part of the program are researches natural and human made of the phenomena in a passive mode. The presence of two spacecrafts, equipped practically by equivalent complexes of the scientific equipment, enables not only to carry out diverse researches of the ionosphere and bottom magnetosphere, but also to distinguish spatial and temporary structure of the observable phenomena.

The complex program of "under satellite" ground observation and experiments includes standard geophysical monitoring and special programs with heating instalation.

 Both spacecrafts, basic APEX and subsatellite MAGION-3,were launched on an elliptical orbit with apogee of 3050 km and perigee of 440 km, with the inclination 82,5 of a plane of an orbit (almost the polar orbit allows to carry out researches in auroral area).

Primary scientific objectives of the project

The most important problems of the project are:

• research of wave radiation of a modulated beam of electrons, generation of whistlers by a beam of electrons in the vicinity of injector and in the region of geomagnetic equator;
• research of dynamics and relaxation of electron and plasma beams in the ionospheric plasma;
• research of processes of charging of space vehicles and its neutralization;
• research of excitation of magnetohydrodynamic and low-frequency waves in the ionosphere by a modulated plasma beam and connected to it phenomenon of a stimulated precipitation of trapped particles;
• research of the nature of electrodynamic connection of electromagnetic waves in the magnetosphere and ionosphere;
• search of nonlinear wave structures as electromagnetic solitons in the disturbed ionosphere; creation and study of strong local perturbations of magnetospheric plasm, asuch as double layers and shock waves;
• study of the transformation of waves in a strongly non-uniform plasma, in particular of ballistic effects in wave barriers transparency;
• research of processes of transformation of energy in the << solar wind - magnetosphere - ionosphere >> system .

Scientific instrumentation of APEX project
 

The diagnostic part of the set of scientific equipment of APEX represents a complete set of scientific devices, allowing to carry out measurements of micro- and macroparameters of thermal and suprathermal plasma components, to measure space-energy distribution of particles, electric and magnetic fields, analyse variable and constant electromagnetic fields and radiations, measure optical emissions.

 The important peculiarity of APEX is the presence of a subsatellite MAGION, equipped by its own complex of  scientific equipment, which have practically the same opportunities to a plasma and fields measurements as the main one.

Active experiments utilise modulated electron beam accelerator and source of modulated xenon plasma beam on the main spacecraft APEX. The choice of the parameters of the electron accelerator was determined by that in different magnetic force tubes and at different heights. Various resonant conditions for the interaction of waves with beams are available. As is known from rocket experiments, resonant conditions can be used more effectively if the beam is previously modulated at the resonant frequency.

Except the active means and diagnostic equipment APEX also includes an additional ( to the basic configuration of the spacecraft) telemetry system STO-AP,which was developed by the experts of Hungary, former USSR, Poland and Czech republic.. The system STO-AP provides the interface for the devices, management of modes of operations, preliminary processing of the scientific information, independent control of onboard experiments, formation of the TM-frames and transfer of the telemetry information to the groundbased stations at Czech Republic, Russia and Germany.