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Results are presented from an active experiment on the injection of charged particle beams into the ionospheric plasma. The experiment was carried out in 1992 onboard the Intercosmos-25 satellite and the Magion-3 daughter satellite (APEX). A specific feature of this experiment was that both the ion and electron beams were injected upward, in the same direction along the magnetic field. The most interesting results are the excitation of HF and VLF-LF waves and the generation of fast charged particle flows, which were recorded on both satellites.

Results of active experiments on electron beam injection from the Intercosmos-25 satellite into the ionospheric plasma are presented. A quasistatic magnetic field and the VLF-wave magnetic component are excited when an unmodulated electron beam with a current of I be ⋍0.1 A and energy of ɛ be = mv 2 /2⋍10 keV is injected into the ambient plasma. The magnetic field excitation is attributed to the onset of plasma gradient instabilities.

Beam-plasma instabilities in the ionosphere caused by charged particle beams and Xe-neutral gas release are investigated. Special attention is paid to the injection into background plasma of an unmodulated electron beam with a current Ibe ≅ 0.1 A and energy εbe = mv22 ≅ 10 keV. Complex analysis of this problem is carried out with special data processing and with an approach similar to a laboratory-style experiment. The processes of ionospheric plasma heating, longitudinal plasma wave excitation and the analysis of thermal plasma ion disturbances during 1-s pulsed direct current (dc) injections are considered.

Wave and plasma observations were made in a close vicinity of a xenon gun, carried at altitudes near 500 km in the APEX-experiment. Wideband noise associated with neutral gas releases and steady beam currents were detected. In modulation regime even and odd harmonics of the beam modulation frequency were observed. A delay in wave emissions after modulated beam injection was terminated was also detected. This effect was accompanied by electron temperature and density disturbances as measured by a plasma density and temperature device.

Cosmos-1809 satellite data on ELF emissions, plasma density, Ne and variations dNe in the ionosphere above the Spitak earthquake zone during a period of enhanced aftershock activity are presented. The data show that small-scale plasma inhomogeneities with dNeNe ≈ 3–8% and with a characteristic scale of 4–10 km along the orbit are excited on geomagnetic field tubes connected to the epicentral region, simultaneously with earthquake related ELF emissions. A generation mechanism for such inhomogeneities under the influence of seismic activity in terms of the dissipative instability of acoustic-gravity waves in the ionosphere is proposed.

Khabarovsk transmitter signals (15.0 kHz, 48°N, 135°E) were observed on the high‐altitude (∼15000 km) Dynamic Explorer 1 (DE 1) and the low‐altitude (∼960) km COSMOS 1809 satellites during a 9‐day period in August 1989. On 7 out of 9 days the linear wave receiver (LWR) on the DE 1 satellite detected signals from the Khabarovsk transmitter. In addition, the DE 1 satellite also detected signals from the Alpha transmitter (11.9‐15.6 kHz) in Russia and an Omega transmitter (10.2‐13.6 kHz) in Australia, as well as natural VLF emissions such as hiss, chorus, whistlers, and wideband impulsive signals. On two days, August 23 and 27, 1989, observations of the Khabarovsk transmitter signals were simultaneously carried out at high altitude on the DE 1 satellite and at low altitude on the COSMOS 1809 satellite. Analysis of data from these 2 days has led to several new results on the propagation of whistler mode signals in the Earth’s magnetosphere. New evidence was found of previously reported propagation phenomena, such as (1) confinement of transmitter signals in the conjugate hemisphere at ionospheric heights (∼1000 km), (2) observation of direct multipath propagation on both DE 1 and COSMOS 1809, (3) detection of ionospheric irregularities of ≤ 100 km scale size with a few percent enhancement in electron density, believed to be responsible for the observed multipath propagation. We report the first detection of an exterior caustic surface near L ∼ 3.5 for VLF ground transmitter signals injected into the magnetosphere; the location of the caustic surface depended on the signal frequency, and the electric and magnetic fields decreased by several hundred decibels per L shell in the dark (shadow) side of the caustic. We also report the first direct detection of a magnetospheric duct at L = 2.94 which was believed to be responsible for the ducted propagation of Khabarovsk signals observed on the COSMOS 1809 satellite; the measured duct parameters were: ΔL ∼ 0.06 and ΔNe, ∼ 10 ‐ 13%. The duct width at the equator was ∼367 km. Our study also indicates that duct end points can extend down to at least ∼1000 km. The peak electric and magnetic fields of ducted Khabarovsk transmitter signals at ∼1000 km were 520 µV/m and 36 pT respectively. Estimated field strengths of these signals inside the duct at the geomagnetic equator were 57 µV/m and 12 pT for electric and magnetic field respectively. The results of two‐dimensional ray tracing simulations were consistent with the observations of the nonducted whistler‐mode propagation of Khabarovsk (15 kHz) and Alpha (11.9 kHz) signals from the transmitter location to the DE 1 and COSMOS 1809 satellites. Our results have direct implications for the question of accessibility of waves injected from the ground to various regions of the ionosphere and the magnetosphere. In situ measurements of electric and magnetic fields of Khabarovsk transmitter signals inside a duct may well prove to be the critical measurements needed to differentiate between the small signal and large signal theories of wave particle interactions.

Spectral broadening of signals from a ground-based VLF transmitter was observed onboard the Magion-3 sub-satellite during electron beam injection from the lntercosmos-25 (APEX) satellite. Broadening of the order of 300–500 Hz was apparently correlated with the 2 s-periodic sequence of the electron gun pulses which were modulated in amplitude with frequencies 30.5 < fm < 31,250 Hz. No effects were found for those electron gun pulses with fm = 62.5, 125 and 250 kHz.

Two rocket experiments KOMBI-SAMA with plasma injection at height 100–240 km were performed in August 1987 in the region of Brazilian magnetic anomaly (L = 1.25). The launching time of the rocket was determined so that plasma injection was at the time when satellite COSMOS 1809 passed as close as possible to magnetic tube of injection. Caesium plasma jet was produced during ≥ 300 s by electric plasma generator separated from the payload. By diagnostic instruments on board of the rocket and the satellite were registered energetic particle fluxes and plasma wave activities stimulated by plasma injection. When the satellite passed the geomagnetic tube intersecting the injection region an enhancement of ELF emission at 140 Hz, 450 Hz by 2 times was registered on board the satellite. An enhancement of energetic particles (E > 40 keV) flux by 4–5 times was registered on board the rocket. Observed ELV emission below 100 Hz is interpreted as generation of oblique electromagnetic ion-cyclotron waves due to drift plasma instability at the front of the plasma jet.