Vol 51, No 9 (2025)

The Gas Dynamic Trap (GDT) facility is an open magnetic trap for plasma confinement. It is a variation of the Budker-Post mirror machine (probkotron), with the distance between the mirrors exceeding the characteristic path length of ions before scattering into the loss cone, and with a high mirror ratio. Under these conditions, the plasma particle confinement mechanism is similar to that of a collisionless gas in a vessel with a small opening, and the plasma confinement time depends linearly on its length and mirror ratio. These systems have potential for several applications in controlled nuclear fusion, the most immediate of which is the D-T neutron fusion source, capable of producing a neutron flux with a power density of several megawatts per square meter. This is required for the materials science research necessary for the design of the first wall of future fusion reactors. The experimental program of the GDT facility includes the study of kinetic and magnetohydrodynamic plasma instabilities, investigation of the behavior of sloshing ions, additional methods for heating and maintaining the material balance in the trap, and the study of the energy balance of the plasma. The paper describes in detail the GDT facility, its Diagnostic Complex, and control system, which is relevant today.

Luminescent materials based on Al₅O₆N doped with Ce³⁺ ions were prepared via plasma-chemical process resulting from a microwave discharge initiated in metal-dielectric powder mixtures. The subthreshold self-non-self-sustained discharge was initiated by microwave pulses with a frequency of 75 GHz, a power of 400 kW, and a duration of 8 ms in Al/γ-Al₂O₃/melamine mixtures. Cerium was introduced in the forms of CeO₂ and Ce(acac)₃H₂O, as well as via pre-doping of γ-Al₂O₃ with Ce³⁺ ions. The kinetic parameters of the plasma-chemical process were determined. The products of the process were studied with electronic microscopy and X-ray diffraction analysis, also their pulsed cathodoluminescence spectra were measured. It has been shown that the rate of the plasma-chemical process and the efficiency of the Ce³⁺ ions incorporation into the resulting phase of aluminum oxynitride Al₅O₆N strongly depend on the nature of cerium-containing precursor.

The possibility of using the PIV (particle image velocimetry) method as an alternative to the existing methods used to analyze the dynamics of solar plasma during a coronal mass ejection is considered. PIVLab software was used to perform a comprehensive analysis of a coronal mass ejection dynamics. The linear speed and the velocity field of the coronal mass ejection were calculated. The study showed that the software is capable of measuring changes in the coronal structure and record the processes that lead to the observed changes.

The dependences of the kinetic and transport coefficients of electrons in argon are calculated using the Monte Carlo method over a wide range of reduced field strengths E/N from 30 to 2000 Td. The obtained results are compared with experimental data available in the literature. It is shown that for argon, the drift-diffusion approximation for calculating the spatiotemporal evolution of the electron density becomes inapplicable in fields larger than ≈ 1000 Td. The results of numerical calculations of electron transport in argon in uniform and inhomogeneous electric fields performed using the Monte Carlo method are also compared with the results of calculations using a previously developed multigroup model.

The experimental studies of the break-through phase of the leader spark discharge in 1.3 m gap are presented. A numerical model is developed that describes the parameters of streamer zone and evolution of leader current during the break-through phase. The dependence of the leader velocity in the break-through phase on the magnitude of the reduced electric field E/N in the streamer zone is obtained. These dependences are compared with the measurement data; it is shown that the leader velocity V_L ∼ (E/N)^3/2. The agreement between the calculated and meas-ured time profiles of the leader current pulses in the breakthrough phase was obtained. It is shown that the main reason for the sharp increase in current at times of 1–2 µs is the increase in the reduced electric field in the streamer zone, associated with a decrease in the length of this zone as a result of the convergence of the leader heads. The field growth leads to an increase in the streamer velocity in the streamer zone, an increase in the leader current and the leader velocity.