SOME RESULTS FROM INTMINS

The experiment can be performed when the electron beam (instrument ISTOCHNIK) and plasma blobs (instrument ARIEL) are injected approximately along or perpendicular to the Earth's magnetic field. There are three modes of operation of the instruments. The first two have different sequences of alternating plasma injections by ARIEL between the EM channel and the thermal channel. In the third mode the electron gun is used, and its EM field may be observed on the ground. The pulses of frequency of 1000 Hz will generate EM waves and its harmonics. These frequencies are in the pass band of the INSPIRE VLF receiver.

The first observations from the INTERBALL-1, the result of the INSPIRE network observations during major operations periods, and results of theoretical calculations of the propagation of electromagnetic waves connected with electron beam injection were implemented.

The results of our theoretical calculations of propagation of the EM waves generated by electron gun are as follows:

For reliable ground-based reception of electric field signal of the ISTOCHNIK instrument at the distances up to several hundred kilometres from the vertical axis from the MIR space station to the Earth surface, under the mean interference level conditions and at middle latitudes, and with any azimuth angles between the station and the reception point, it is necessary:

1. To use the L-shaped antenna with the horizontal and vertical parts oriented along the Earth’s magnetic field. In this case the maximal rigidity of the antenna design should be provided for the reduction of interference arising from its vibration due to the wind. Obviously, it is necessary to match it well with the receiver input and to isolate it carefully relative to the ground because of the high antenna reactance in the VLF-band.
2. To increase the electron gun pulse duration up to D t = 0.5f ^-1 (D t = 5x10^-4 s) and to stabilise their frequency as good as possible.

3. To receive the third harmonic of signal (f₃ = 3 kHz) with minimal possible band width of signal reception and processing. (It is more preferable to change the current pulse parameters up to the values f = 3 kHz, D t = 0.5f ^-1 » 1.7x10^-4 s).

4. To increase the amplitude of current in pulse by one order (up to 7 A). In this case the spectral analysis has to use the width of the frequency band D f not exceeding 1 Hz. Obviously, the required amplitude of current pulse has to be directly proportional to (D f)^0.5 for D f << f_n.

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