Issues with Modeling a Tunnel Communication Channel through a Plasma Sheath

We consider two of the most relevant problems that arise when modeling the properties of a tunnel radio communication channel through a plasma layer. First, we studied the case of the oblique incidence of electromagnetic waves on a layer of ionized gas for two wave polarizations. The resonator parameters that provide signal reception at a wide solid angle were found. We also took into account the unavoidable presence of a protective layer between the plasma and the resonator, as well as the conducting elements of the antenna system in the dielectric itself. This provides the first complete simulation for a tunnel communication channel. Noise immunity and communication range studies were conducted for a prospective spacecraft radio line.

Влияние анодной и катодной плазмы на работу электронного диода со взрывоэмиссионным катодом

The results of modeling and experimental investigation of the formation of anode and cathode plasmas in a vacuum diode with an explosive-emission cathode during the generation of a pulsed electron beam with a current density of 0.3-0.4 kA/cm^2 and an accelerating voltage of 300-500 kV are presented. It is shown that the concentration of the anode plasma does not exceed 10^10 cm^-3 and it does not significantly contribute to the operation of the diode. However, the complete desorption of molecules from the working surface of the explosive-emission cathode and the high efficiency of shock ionization of atoms ensure the formation of a cathode gas plasma with a concentration of 10^16 cm^-3. It is found that the charge of the explosive-emission plasma layer is significantly less than the charge of the electron beam and the main source of electrons is not an explosive-emission plasma, but a cathode gas plasma. In this case, the electron current is limited by the concentration of the cathode plasma. The use of a cathode with a developed surface (a cathode with a carbon fabric coating) allows increasing the total charge of the electron beam by more than 1.5 times without changing the cathode diameter and the anode-cathode gap.

On the accuracy of aurora visible boundaries in the OVATION Prime (PC) model

Оценка положения экваториальных границ аврорального овала при разных магнитосферных условиях, несёт в себе информацию о формирующихся плазменных структурах, глубине их проникновения во внутреннюю магнитосферу, движении внутренней границы плазменного слоя и т.д. Развитие алгоритмов определения положения видимой экваториальной границы аврорального овала является важной частью исследований, связанных с разработкой моделей химического состава ионосферы, моделей авроральных высыпаний частиц и оценки точности этих моделей. Немаловажную роль исследования полярных сияний (прогноз, интенсивность, положение) играют и для развития туристического сегмента в Арктике и информационных ресурсов служб мониторинга и прогноза космической погоды. В рамках исследования оценки точности положения видимых границ овала сияний в моделях авроральных высыпаний частиц была выбрана наземная наблюдательная сеть оптических камер всего неба проекта THEMIS, запущенная в 2008 г., и модифицированная модель OVATION Prime (PC), разработанная в отделе Геофизики ФГБУ «ААНИИ использующая в качестве входного параметра наземный индекс полярной шапки (PC-индекс). The location of the equatorial boundaries of the auroral oval under different magnetospheric conditions contains information about the forming plasma structures, the depth of their penetration into the inner magnetosphere, the motion of the inner boundary of the plasma layer, etc. The development of methods and algorithms for determining the position of the visible equatorial boundary of the auroral oval is an important part of research related to the development of models of the chemical composition of the ionosphere, models of auroral particle precipitation, and assessment of the accuracy of these models. Research of aurora borealis (forecast, intensity, position) also plays an important role for the development of the tourist segment in the Arctic and information resources of space weather monitoring and forecasting services.

Generation of dense and well-collimated positron beam via ultra-intense laser colliding with a flying plasma layer

With the forthcoming 10-100PW laser facilities, laser-driven electron-positron-pair production has gained particular interest. Here a scheme to enhance the generation of dense electron-positron-pairs is proposed and numerically demonstrated, employing double laser pulses at the intensity level of 10^23 W cm^(-2). The first laser accelerates a thin foil to a relativistic speed via the radiation-pressure-acceleration mechanism and a counter-propagating laser irradiates this flying plasma layer. The simulation results indicate that a high-yield and well-collimated positron beam (~5.5×10^10 positrons/pulse, 8.8nC/pulse) is generated with a large peak density(1.1×10^21 cm^(-3) ) by using tens-of-PW laser pulses.

A new device for autonomous space devices based on a three-component quantum variometer

The necessity of additional study of magnetic field variations in the magnetic transition layer, in the magnetopause, as well as in the plasma layer and in the tail of the magnetosphere in a wide range of distances from the Earth is substantiated. To obtain additional information in comparison with the studies that are being carried out in outer space at the present time, it is necessary to simultaneously monitor the magnetic field at various points in outer space. It is also necessary to register the dynamics of changes in the magnetic field in time in space by three components. To accomplish this task, a small-sized three-component quantum variometer with autonomous power supply has been developed for space devices, which can be lost in the course of short-term research. The results of the operation of a quantum variometer are presented.

Surface discharge during electrical explosion of conductors in strong magnetic fields

In experiments on the electrical explosion of conductors in rapidly growing mega-Gaussian magnetic fields, it was found that at the initial stage of the explosion, “hot spots” up to 500 pieces/mm2 were recorded on the surface. At a later stage, a plasma layer was formed on the surface of the conductor, in which filaments, that is, current channels, were formed. In this work, on the basis of the ecton theory, a model of the development of a surface discharge is constructed. The model makes it possible to estimate, firstly, the magnitude of the current flowing through the surface plasma, and secondly, the thickness of the plasma layer.

Lead evaporation by VUV radiation of various spectral ranges

The results of an experimental study of the plasma formed by the evaporation of the lead target in the field of powerful broadband VUV radiation are presented. A pulse light-erosion magnetoplasma compressor (MPC’s) discharge is used as a model source of VUV radiation. “Gas filtration” of radiation is used to control the spectral composition – the discharge takes place in pure inert gases: in argon at 200 torr and neon at 400 torr. This allows us to manage the spectral distribution of radiation energy and to limit the energy of quants which irradiate the lead target with the first ionization potential of buffer gas. Shadow photography, toeplergrathy, double exposure laser holographic interferometry are used for diagnostics. Experimentally established different distribution of parameters in the lead plasma depending on the spectral composition of the impact radiation (the composition of buffer gas). It is shown that when the energy of quants increases (above the lead second ionization potential), a more even heating of the plasma layer is realized.

Subnanosecond breakdown of air-insulated coaxial line initiated by runaway electrons in the presence of a strong axial magnetic field

Flow of runaway electrons (RAEs) propagating in a radial, air-filled gap of coaxial line (CL) changes the dynamics of breakdown in the field of traveling voltage pulse. However, despite the effect of RAEs, breakdown does not occur if subnanosecond pulse is less in duration and amplitude than some values. In this work, we study the influence of an external axial magnetic field (B z) on the breakdown development. We demonstrate the transformation of the voltage pulse reflection from the ionized (breakdown) zone with changing B z. Due to gyration of fast electrons in an applied magnetic field, the gas region ionized by RAEs does not reach the anode. The ionized bridge between the cathode and anode is gradually replaced by a near-cathode plasma layer representing a discrete, reflecting/absorbing inhomogeneity in the CL.

MODES OF TRANSILLUMINATION OF THE DENSE PLASMA LAYER VIA ELECTROMAGNETIC BEAM

Interaction of the powerful electromagnetic ray of the limited radius with a dense plasma layer was studied viacomputer simulation using the PIConGPU software package in 3D geometry. The characteristic modes of channel formation in the barrier (namely laminar and turbulent) are described. Turbulent mode can be associated with the fast transillumination, observed in laboratory experiments. The channel formation time as a function of the incident beam power and the plasma layer density is studied. Information transparency is also observed at the third harmonic of the incident wave.