Boris Gavrilov

Diamagnetic effect produced by the Fluxus-1 and -2 artificial plasma jet

The purpose of the Fluxus-1 and -2 active experiments is to study plasma jets injected parallel to the magnetic field and to study the interaction of these jets with the magnetic field. The experiments were conducted using a shaped-charge device, known as an explosive type generator (ETG), that produced an artificial aluminum plasma jet. In Fluxus-1 and -2 the jet was injected nearly parallel to the geomagnetic field at an altitude of 140 km toward an instrumented diagnostic payload located about 100 m away from the ETG. A ∼50% reduction in the magnetic field was observed as the plasma jet passed by the diagnostic payload. Comparisons of 3-dimensional simulation results with the observed magnetic field perturbations suggest that the Fluxus-1 plasma jet was ∼30° from the magnetic field direction while the Fluxus-2 plasma jet was directed nearly parallel to the magnetic field.

observation of auroral emissions induced by artificial plasma jets

In this paper we present ultraviolet to near infrared spectrographic observations of high-speed artificial plasma jet interactions with the ionosphere. The plasma jets were injected quasi-parallel to the magnetic field at an altitude of 140 km during the Fluxus-1 and -2 experiments. The jets contained aluminum ions and were generated using a shaped-charge device known as an Explosive Type Generator (ETG). Satellite-based spectrographic observations of the plasma jet show typical auroral emission features associated with electron impact excitation. The auroral features include emission at 135.6 nm (OI) and 557.7 nm (OI). The 135.6 nm emission was prompt while the 557.7 nm was observed for 5 seconds. The most likely source of these auroral emissions are ionospheric and magnetospheric electrons that neutralize the plasma jet.

Electric Field, Magnetic Field, and Density Measurements on the Active Plasma Experiment Sounding Rocket

High-resolution, in situ measurements of dc and wave electric fields, magnetic fields, and plasma number density have been gathered by instruments on a diagnostic payload at which a high-velocity, overdense aluminum ion beam was directed from a separate payload spaced 468 m away. The experiment, called the Active Plasma Physics Experiment, was carried out in the Earths high-latitude ionosphere at 360-km altitude using a sounding rocket. The experimental data clearly show a large diamagnetic cavity with a 93 % depletion of the Earths magnetic field within a narrowly confined ( 1.5 V/m perpendicular to the magnetic field were observed that represented both the E × B bulk plasma velocity and a magnetosonic wave, which preceded the arrival of the beam that was also evident in the AB magnetometer data. The electric field data also show the presence of electric fields parallel to the magnetic field, including a bipolar electric field signature presumably set up to ensure current continuity. Other plasma waves associated with the release include Alfven perturbations, intense broadband turbulence extending to frequencies beyond 1 MHz, whistler-mode electromagnetic emissions at the ambient O + lower hybrid frequency, and ion acoustic turbulence. The measurements provide a self-consistent picture of the electrodynamics surrounding a high-velocity, overdense ion beam released in the high-latitude ionosphere.

North Star Plasma-Jet Experiment Particles and Electric and Magnetic Field Measurements

The results of measurements of magnetic and electric fields, plasma ions energy, and plasma density during the Russian‐American North Star active experiment are presented. The experiment was carried out in the auroral ionosphere on 22 January 1999. A Black Brant XII rocket, having two explosive aluminum plasma generators plus scientific payloads onboard, was launched at 13:57:03 UT from Poker Flat, Alaska. Two plasma-jet injections across the magnetic field were made at the altitudes 280 and 360 km, respectively. Before injection 1, an air cloud was released to increase jet ionization. At injection 1, the maximum plasma density exceeded the density at injection 2 by two orders of magnitude. This can be explained by charge stripping of aluminum atoms when the jet propagated through the dense air cloud. Only at injection 1 was complete expelling of the magnetic field by the plasma jet observed. A weak plasma deceleration was indicated by magnetic field compression before the jet front. At injection 2, the magnetic field was weakened only by 1%. A polarization electric field E = −V × × B generated field-aligned currents, which involved the ionospheric plasma in motion, and the plasma jet efficiently decelerated.

North Star Plasma-Jet Space Experiment

The objective of the Active Plasma Experiment North Star mission was to study the interaction of artificially produced aluminum ion plasma jets with the space environment. Two separate plasma jets were injected almost perpendicular to the local magnetic field during the North Star experiment. The jets were created using an explosivetype generator designed to produce a high-speed (7‐42-km/s) aluminum ion plasma jet with plasma densities exceeding 10 9 cm −3 at a distance 170 m from the plasma-jet source. The first plasma-jet injection occurred at an altitude of 360 km and was preceded by the release of an artificial air cloud. The second injection occurred at an altitude of 280 km and did not include the air cloud. Interactions of the plasma jet with the local space environment and artificial air cloud were monitored using instrumentation on three diagnostic payloads, ground-based optical sensors, and space-based optical sensors. An overview is provided of the experiment, along with a summary of the principal results from the mission.

Active Plasma Experiment: North Star Particle Data

We report on data from particle instruments making in situ sounding rocket measurements of the particle environment within and near an aluminum plasma jet caused by an explosion in the auroral ionosphere. The Active Plasma Experiment sounding rocket was launched to an altitude of 350 km from the Poker Flat Research Range in January 1999. The payload separated after launch into observing payloads and two explosive plasma jet generators. During the flight, the two explosive packages were detonated, and the observing payloads studied the surrounding environment. The particle instruments measured the resulting plasma jet from a distance of approximately 500 m. The instruments measured ions from 10 to 420 eV, electrons from 10 to 6000 eV, and low-energy electrons from 2 to 1200 eV. After each explosion, the particle instruments recorded the passage of a burst of material past the spacecraft. Analysis of mass-dependent effects, plasma β, and critical ionization velocity parameters are presented, together with a comparison to earlier experimental observations. In particular we note that the duration of the enhanced ion fluxes is controlled by the jet velocity and drops sharply when the jet velocity falls below the critical ionization velocity for each ion, with the peak ion fluxes only observed while v j e t > V c r i t (O+).

Dynamics of the Active Plasma Experiment North Star Artificial Plasma Jet

Active Plasma Experiment North Star was launched from Poker Flat Research Range, Alaska, on 22 January 1999 at 13:57:03 UT, with two explosive-type generators that produced an artificial aluminum plasma jet. The purpose of this experiment was to study the interaction of the artificial plasma jet with the ambient plasma. The first release occurred at 363 km, and a ∼90% reduction of the geomagnetic field was observed on three separate daughter payloads. The diamagnetic signatures suggest that the plasma cloud was highly localized (i.e., cloud dimensions ∼Al + gyroradius) traveling with a velocity of roughly 25 km/s perpendicular to the geomagnetic field. A hybrid code simulation provided an estimate of the plasma distribution and a qualitative description of the evolution of the plasma cloud. The simulation showed that the plasma cloud polarized and E x B drifted while transferring momentum to the ambient plasma via an Alfvenie disturbance. The model results are in good qualitative agreement with data from the plasma diagnostics payload.

Plasma Jet Motion Across the Geomagnetic Field in the “North Star” Active Geophysical Experiment

The active geophysical rocket experiment “North Star” was carried out in the auroral ionosphere on January 22, 1999, at the Poker Flat Research Range (Alaska, USA) using the American research rocket Black Brant XII with explosive plasma generators on board. Separable modules with scientific equipment were located at distances of from 170 to 1595 m from the plasma source. The experiment continued the series of the Russian–American joint experiments started by the “Fluxus” experiment in 1997. Two injections of aluminum plasma across the magnetic field were conducted in the “North Star” experiment. They were different, since in the first injection a neutral gas cloud was formed in order to increase the plasma ionization due to the interaction of neutrals of the jet and cloud. The first and second injections were conducted at heights of 360 and 280 km, respectively. The measurements have shown that the charged particle density was two orders of magnitude higher in the experiment with the gas release. The magnetic field in the first injection was completely expelled by the dense plasma of the jet. The displacement of the magnetic field in the second injection was negligible. The plasma jet velocity in both injections decreased gradually due to its interaction with the geomagnetic field. One of the most interesting results of the experiment was the conservation of high plasma density during the propagation of the divergent jet to considerable distances. This fact can be explained by the action of the critical ionization velocity mechanism.

Remote sensing of ELF/VLF radiation induced in experiments on artificial modification of the ionosphere

In 2012, remote measurements of electromagnetic signals in the ELF/VLF band were taken at different points in Russia during experiments on artificial ionospheric modification with the powerful HF wave at the EISCAT heating facility (Tromsø, Norway). The use of the new, highly sensitive magnetometric equipment allowed signals with an amplitude of a few femtoteslas to be recorded at a distance of up to 2000 km from the source. Analysis of the measurement results discovered substantial differences in the amplitude-phase characteristics of the signals, which were caused by a change in helio-geophysical conditions in the region of heating and along the signal passage route, and features of signal propagation, which are related to their mode of guided propagation, the directivity of the source, and angles of reception.

Spatiotemporal distributions of the electron density in the ionosphere by records of the total electron content and phase of VLF radio signals

Features of the structure and dynamics of the ionospheric plasma are studied in a comparison the ionospheric total electron content measurements with the phase and amplitude measurements of VLF–LF radio signals on global and regional paths. The ionospheric structure over Europe is reconstructed. The spatiotemporal dynamics of moving ionospheric disturbances under conditions of a powerful geomagnetic storm of March 17, 2015, is examined based on the reconstruction results. Analysis of the phase variation of VLF radio signals, together with the TEC measurement data, is not only an additional tool in the study of the dynamics of ionospheric disturbances; it also makes it possible to estimate electron density disturbances in different ionospheric layers.