Peculiarities of the environment disturbance during the electron beam injection from the rocket

The paper presents some results obtained when a beam of electrons (energy 2 to 3.5 keV, current 0.2 to 0.4A) was injected from aboard the rocket at 100 to 150 km.At the moments the beam was injected perturbations of the near-rocket region are observed with a cross-section of about 500 m, it is much larger than the region over which the injected beam is extended.The appearance of the above region can be explained by the interaction of accelerated ions with the surroundings; the ions are generated during the positive rocket charge neutralization owing to discharge mechanisms. It is confirmed by direct measurements of the rocket potential which is about 2 kV near the apogee.     

Ionospheric electron heating by a rocket borne electron accelerator

A “mother-daughter” rocket code-named “Electron 2” was launched from And?ya, Northern Norway in November, 1978. The “daughter”, carrying a 10 keV electron accelerator, was separated from the “mother” payload with a speed of 0.4 m/s. A series of plasma diagnostic instruments were included on the “mother” to study effects produced by the interaction between the electron beam and the ionospheric plasma. Results obtained by two different plasma probes are presented. It was found that pronounced changes in the ambient electron population took place in regions penetrated by the electron beam. Estimates of the dimensions of the disturbed region are presented.     

Registration of ELF waves in rocket-satellite experiment with plasma injection

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.     

The glow of the night ionosphere due to energetic ion beams

This paper discusses photometric measurements made of the ionospheric excitation of the line $\text{λ = 5577}\text{A}\text{?}$ at the time of electron beam injection from a rocket into the Earth's ionosphere. The gradual increase of the glow intensity per impulse occurs due to accumulation of the energy of excited states of N₂(A³Σ⁺_u) and O(′S) during their lifetimes. The large disturbed zone in the near-rocket environment (size >500 m) is connected via the interaction of ions accelerated in the rocket potential field with ionospheric components. The glow intensity modulation is observed at a height of ～98 km during the electron beam injection simultaneously with the ignition of the beam-plasma discharge (BPD). The intensity minima are explained by a decrease of the energy of accelerated ions due to effective neutralization of the rocket body by the BPD plasma. The height profile of the glow intensity revealed two maxima at heights of ～103 km and ～115 km. The second maximum (at ～115 km) indicates that, at these heights, both collision and collision-free mechanisms of accelerated ion energy transport to ionospheric components exist.     

Energy deposition in the upper atmosphere in the EXCEDE III experiment

The EXCEDE III sounding rocket flight of April 27, 1990 used a 18 Ampere 2.5 keV electron beam to produce an artificial aurora in the region 90 to 115 km. A “daughter” sensor payload remotely monitored the low-energy X-ray spectrum while scanning photometers measured the spatial profile of prompt emissions of N₂⁺ (1N) and N₂ (2P) transitions (3914Å and 3805Å, respectively). Two Ebert-Fastie spectrometers measured the spectral region from 1800 to 8000Å. On the “mother” accelerator payload, the return current electron differential energy spectra were monitored by an electrostatic analyzer (up to 10 keV) and by a retarding potential analyzer (0 eV to 100 eV). We present an overview of the results from this experiment.     

Laboratory experiments on spacecraft charging and its neutralization

Simulation experiments on spacecraft charging in space plasma and its neutralization are performed in relation to the electron beam experiment (SEPAC) on Space Shuttle Spacelab 1. A spacecraft simulator or a spherical probe is immersed in a magnetized plasma and a positive high voltage with respect to the plasma is externally applied to it. The current-voltage characteristics follow quite well with the theoretical model of Parker and Murphy [1] in the low voltage, low pressure region. When the voltage rises to more than the ionization potential of the surrounding neutral gas, it departs from the model and the effect of plasma production by the electron current becomes very important. The same kind of ionization effect as this has also been observed in our rocket experiments with an electron beam. The enhancement of the ionization effect by an additional neutral gas injection causes a considerable suppression of the potential rise of a spacecraft emitting an electron beam. This is demonstrated with the SEPAC accelerators in a large space chamber experiment.     

Electron beam experiments in Japanese satellites and rockets

Electron beam experiments in space that have been done and planned in Japan are reviewed. 200eV, 1mA electron beam is emitted from a satellite and several types of wave excitation such as UHF and ω_ce have been observed. The satellite potential and the energy spectrum of returning electrons are measured by Langmuir probes and electrostatic energy analyser. In rocket experiments of K-10-11, K-10-12, K-9M-57, K-9M-58, K-9M-61 and K-9M-66, several types of electron guns were used whose power ranges from 1mW to 1KW. The rocket potential was measured by Langmuir probes and floating probes and optical line emission measurement and wave measurements were also done. The rocket potential was not so high as expected from the balance with ionospheric plasma but strongly affected by the plasma production by the emitted electron beam and return electrons.     

Very low frequency waves stimulated by an electron accelerator in the auroral ionosphere

The sounding rocket POLAR 5 carried a 10 keV electron accelerator and various diagnostic instruments in a mother-daughter configuration. Onboard wave receivers recorded several types of VLF wave phenomena directly associated with the operation of the accelerator, with delays from 5 to 50 ms after the injection of the electrons. These delayed after-effects range from broadband noise, f > 3 kHz, observed above 170 km, through narrow band emissions at 2 and 5.6 kHz which appeared when the rocket crossed a region with precipitation of energetic electrons, to emissions covering frequencies from 3–4 to well above 100 kHz observed within the E-region (150-95 km). The latter was also associated with apparent changes in electron density. The observed emission properties indicate that the region perturbed by the beam and the neutralizing return current to the daughter may be a favoured generation region.     

Beam-plasma discharge in near rocket region

The model of beam-plasma discharge near the rocket following electron beam injection into the ionosphere is presented. The dependence of discharge plasma density on neutral atmosphere concentration and beam parameters is found. Radioemission and luminiscence intensities from discharge are estimated. The model is consistent with the data of ARAKS and “Zarnitsa-2” experiments.     

Results of ZARNITZA-2, a rocket experiment on artificial electron beam injection in the ionosphere

The rocket experiment ZARNITZA-2 on artificial electron beam injection in the ionosphere was carried out on September 11, 1975. Great attention was paid to the study of phenomena occurring in the near-rocket region. The results of the experiment are discussed in terms of a beam plasma discharge.     

Injection of 40-kHz-modulated electron beam from the satellite: II. Excitation of electrostatic and whistler waves

Beam-plasma interaction effects are studied during the active space experiment with electron and Xe-ion beam injections in an ionospheric plasma. Permanent 40-kHz-modulated electron beam injection occurs simultaneously with a xenon-ion beam injected by the Hall-type plasma thruster operating in a square-pulse mode (100/50 s for a job/pause duration). The unusual behavior of the background charged particle fluxes and wave activity stimulated during the beam-plasma interaction have been registered by the scientific instruments onboard Intercosmos-25 station (IK-25) and Magion-3 subsatellite. The longitudinal and electromagnetic wave instabilities and their mutual relationship are considered in order to explain the observed effects. The excitation of electrostatic waves by the electron injection has been considered for different resonance conditions near the linear stability boundary. Beam-driven electromagnetic instability is responsible for the backward-propagating whistler waves excited via cyclotron resonance. Competition of these two beam instabilities is one of the subjects of the present study.     

Specific features of electron distributions at altitudes of 400 km

New experimental data obtained on the orbital station ‘MIR’ in 1991 during solar maximum are discussed. Electron fluxes with E_e>75 keV were registered for three different directions as well as for electrons with E_e>300 and 600 keV. Spatial and time distributions of electron fluxes in the trapping region are presented. In the inner radiation belt an additional maximum is observed at L=1.25–1.35, and the fluxes in the 22-05^h MLT interval are 2–3 orders of magnitude smaller, than during other local times. In this region a flattening of the electron spectrum is observed. The results obtained were compared with the AE-8 model.     

Response of the electron energy distribution to an artificially emitted electron beam: Apex experiment

The paper is based on the electron and ion energy spectra measurement on board the main spacecraft of the APEX mission. During the active phase of the experiment an intense electron beam was emitted from the main satellite. The basic cycle of the electron injection is formed by current pulses of different frequencies, duration and intensity. The spacecraft potential changes due to the gun operation were compensated by a low energy Xe plasma generator. The data show that the response of the environment to the beam emission depends not only on injection parameters but on the spacecraft position and orientation with respect to the magnetic field as well. The typical response is an increase of the intensity of the low energy (less than 1 keV) electrons in all directions. In addition, strong field aligned fluxes of electrons and/or ions are observed with energies below the gun energy. An attempt to classify different types of response and to find possible mechanisms which can explain the observed phenomena is made in the present paper.     

Probing the magnetosphere with artificial electron beams

Since 1970 the Minnesota group has completed five sounding rocket experiments in which electron beams were injected into the magnetosphere at ionospheric heights and the interaction of the beams with the nearby and distant magnetosphere studied. By the technique of precisely locating conjugate region beam echoes the distant electric and magnetic field structures were studied by mapping into the local ionosphere. Ionospheric fields were measured directly for comparison. Subjects studied included gradient and curvature drifts, electric field drifts, electron pitch angle diffusion and other types of interactions with the tail plasma sheet region and the nearby ionosphere and atmosphere. The beams were also studied by plasma wave and ground-based electromagnetic detectors, by ground-based low light level television techniques and by extensive on-board rocket x-ray, photometer and particle detectors. Vehicle potentials and neutralizing processes and beam-ionosphere interactions have also been studied but will not be discussed in this paper.     

Rocket borne electron accelerator results pertaining to the beam plasma discharge

Three flights of rocket borne electron accelerators have yielded some results concerning the Beam Plasma Discharge (BPD). The first flight, E||B, from Churchill carrying an accelerator of 2 and 4 keV electrons, produced a spectrum of whistler mode waves which was identical with that produced in a large vacuum chamber, and which we know to be an indicator of BPD. The second, Echo V, launched from Poker Flat, Alaska, carrying an accelerator of 25–35 keV electrons, produced wave emissions at 3–3.5 MHz observed on the ground. Our interpretation is that BPD was not or was weakly produced. In the third flight, NB³-II launched from Churchill with an accelerator of 2, 4 and 8 keV electrons, wave emissions well above the ambient plasma frequency were observed from a separated payload, but very close to the beam, and are interpreted as demonstrating BPD.     

Negative body potential as result of modulated electron beam emission into ambient plasma

Two different processes play an important role during emission of pulsed electron beam from a satellite: the positive charging of the spacecraft by emitted electron current and the body neutralization by ambient plasma electrons (mainly in pauses between electron pulses).

The injection of modulated electron beam (pulses of 2μs duration, E=8keV, I=0.1A and 25μs repetition) was carried on in the APEX Project. A simple computer model of this process for APEX scenario was performed.

The results show that after primary positive charging (during gun operation) a significant negative charging (in pauses between pulses) caused by neutralization process by ambient plasma with fp>2MHz takes place.     

Rocket observations of propagating waves in the night time equatorial F-region over Brazil

A Brazilian SONDA III rocket carrying plasma diagnostic experiments was launched from the Brazilian rocket launching stations in Alcântara (2.31°S, 44.4°W Geog. Lat.) to measure the height profiles of electron density, electron temperature and the ambient electric field. High frequency capacitance probe was used to measure the height profile of the electron density and the Langmuir probe was used to measure the electron density and the spatial structures of plasma irregularities. An electric field double probe was used to measure the electric field fluctuations associated with the F-region plasma irregularities. Spectral analysis of the fluctuations in electron density and electric field indicated the presence of propagating waves in the night time F-region over a large height range. The electron temperatures estimated from the LP data showed abnormally high values in the base of the F-region during the upleg of the rocket and practically normal values in the same height region during the downleg. A brief study of the characteristic features of the spectra of electron density and electric field fluctuations and the associated electron temperature variations are presented and discussed here.     

Energetic electron fluxes stimulated with pulsed injection of plasma in the ionosphere

Two active experiments have been carried out with a plasma gun on the MR-12 rocket launched from Volgograd. Plasma blobs were injected along (1 experiment) and transverse (2 experiment) the magnetic field lines. In both experiments, the increase of the energetic electron fluxes was registered: in the first experiment it was 2–3 times, and in the second one 10–40 times, larger than the background fluxes before injection. The changes of the spectrum of the energetic electron pulsations have been found also.     

Two dimensional simulation of amplitude modulated electron plasma waves

Highly modulated waves near electron plasma frequency with both parallel and perpendicular polarization have been observed near diffusion region at dayside and in the tail region. In this paper, two dimensional Particle-In-Cell (PIC) simulation was performed to study the possible generation mechanism of these modulated electron plasma waves. It is shown that weak beam instability could generate the modulated Langmuir wave and the ambient magnetic field plays an important role in the formation of modulation. When the weak beam has loss cone distribution, highly modulated upper hybrid waves are generated and propagate with large angle to the ambient magnetic field. The properties of these modulated waves are discussed and compared with observations.     

哨声模合声波与地球同步轨道高能电子通量增强事件事例研究

局部加速机制是磁暴期间地球外辐射带高能电子通量增强事件发生的重要原 因. 此加速机制需要两个基本条件, 一是存在种子电子, 二是存在能与种子 电子产生共振的加速波动, 包括哨声模合声波. 通过对2004-2006年 Pi1地磁脉动持续时间与种子电子通量的相关性分析, 更明确提出Pi1地磁脉 动的持续时间可以作为种子电子通量的指示剂. 通过对三个磁暴事例地球同 步轨道的种子电子通量、高能电子通量及哨声模合声波变化情况的分析, 发 现在高能电子通量较强的事例中, 均观测到较高的种子电子通量和较强的 哨声模合声波, 这在一定程度上验证了哨声模合声波对种子电子的回旋加速 机制, 且合声波强度与高能电子通量有正的相关性.