The processes on the ionosphere-magnetosphere boundary are a subject of investigation by a lot of spacecraft for many years thanks to, among others, their connection with the phenomena observable on the Earth. Of particular interest is the fine structure of this region, which requires simultaneous measurements with both energy and spatial resolution.

The energy and angular distributions of charged particles can bring further information on the nature and spatial scales of magnetospheres processes. The simultaneous observations of space/energy electron and ion distributions are very important for the diagnostics of the nature and sources of particle precipitation's and analysis of processes which develop at ionosphere and inner magnetosphere.

The PAN-experiment is intended for investigation of energy-space distributions of ion and electron fluxes with energies from tens electron-volts up to tens kiloelectron-volts. It permits the fast measurements of energy and angular parameters of charged particles in the range 40eV-40keV.

The submitted above PAN-2 experiment is the prototype of the PEAS-experiment, successfully carried out according to APEX project 1n 1991-1993 years. The technical parameters of the PAN-2 instrument were considerably improved and this one will allow to get the greater amount of TM-data and accordingly, a scientific results.

 This instrument consists of the two separate subunits: sensor unit and an electronic digital processing unit.

The sensor unit is an electron electrostatic, axially symmetrical, toroidal analyzer. The analyzer itself is composed of three concentric, axially symmetrical electrodes are divided into 12 independent sectors for getting information about space distributions of charge particle fluxes. Since the analyzing voltage was applied only to the central electrode, this analyzer permits a measuring positively and negatively charged particles from 12 directions with the angular resolution of ~20 x 5 degrees in the range of 360 x 5 degrees.

So, such system allows to determine the energy parameters of charge particle fluxes in the space.

The energy range for both types of charged particles must stepped according to the logarithmic scale. The number of steps, duration of each step and the energy scale can chosen in accordance with the telemetry rate and operation mode.

The charge particles emerging from the analyzers are post-accelerated onto the sensitive secondary electron multipliers on the base of a pair of micro-channel plates followed by a sectored anode on 12 positions (each anode’s sector correspond to the entrance of one angular section of the toroidal analyzer).

The special microchannel plates 56 mm in the outer diameter are used in this instrument and ensure the normal capability for operation with the variations of input particle flux intensity by 6 orders up to an output count rate value of ~ several MHz.

 Total mass ~6 - 7 kg

Power consumption ~11-12 W

Sensor sizes (preliminary) ~210x245x250 mm

footprints ~230x190 mm

DPU box sizes (preliminary) ~220x205x150 mm (max)

Input voltage 28 V

Measuring particles - electrons, ions

Range in E/q ~ 40 eV to ~ 40 keV

Intrinsic width in E/q ~ 6-7 %

Numbers of steps in E/q 64 max), 32, 16, (in dependence on operation mode, law of E/q steps - logarithmically)

Field of view 360x5 deg

Intrinsic width in azimuth 360 deg

Intrinsic width in elevation 5 deg

Number of angular sectors in azimuth 12

Azimuths resolution 20 deg

Dynamic range ~ 10E6

Maximum count rate at the peak of a energy distribution ~(2-3)x10E6 1/s

Geometric factor/one input window ~ 0,02 sq. cm*ster

Geometrical factor / total input window ~ 0,24 sq. cm ster

Effective area of input windows ~ 8 sq. cm

Commands ~ 7 - function, ~ 7 - digital