Том 49, № 10 (2023)

The thermonuclear fusion between fast (super-thermal) particles injected in plasma as a neutral beam and the ions of the background plasma is expected to be the main source of fusion neutrons in FNS (fusion neutron source) design based on tokamak. Neutral beam contribution in fusion reactivity and in the total neutron yield depends on the high-energy ion fraction in the integral energy distribution. NESTOR code [1] calculates nuclear fusion rates in the FNS plasma volume, taking into account an external source of high-energy fast ions. Neutral beam model reproduces in detail the actual beam structure in phase space at the injection port plane; while the fast ion distributions in magnetically confined plasma are calculated using a combination of slowing-down classical formulae and magnetic field topology in the tokamak chamber. Here we discuss the issues relevant to the overall neutron production and the contribution of fast ions to the neutron output in plasma.

A new approach to the problem of the passage of the extraordinary wave through the region of the electron–cyclotron resonance in inhomogeneous plasma was considered in the framework of the full set of Maxwell’s equations, taking into account the effects of spatial dispersion and resonance dissipation. For the model one-dimensional geometry, field distributions were calculated in the vicinity of the cyclotron resonance at the second harmonic for the normal incidence of the extraordinary wave and the reflection, transmission, and absorption coefficients were found depending on the parameters of the resonance region. As a result, the fine effect of the reflection of electromagnetic radiation from the cyclotron resonance region in transparent plasma was described and the results were compared with the observations of this effect in the experiments on the microwave heating of the plasma at the L-2M stellarator.

Atomic beam injection is one of the main methods of plasma heating in thermonuclear facilities. An injector of high-energy hydrogen atoms for plasma heating based on the acceleration and neutralization of negative hydrogen ions is being developed at the Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences. The injector uses a surface plasma source, in which a plasma flow is created using a radio-frequency driver: an induction radio-frequency (RF) discharge, ignited inside a cylindrical ceramic chamber when an RF voltage is applied to an external antenna. As a part of this work, a new version of the RF driver is being developed. A protective screen is used to prevent overheating and erosion of the ceramic wall of the driver. The operation of RF driver with different protective screens is studied. These screens reduce the efficiency of RF power transmission into the discharge, but make it possible the operation of the ion source in multi-second or steady-state pulses.

Using the Korteweg–De Vries equation, for background plasma, the distribution functions perturbed by ion-acoustic solitons are calculated. For describing the perturbed distribution functions, the explicit formula is obtained, which is suitable for practical applications. The results are compared with the analytical calculations and simulation results obtained previously.

We present the results of numerical studies of the influence of evaporation of anode material on the main characteristics of an arc discharge. Calculations were carried out for an arc discharge in helium as a buffer gas with high-melting-point (using graphite as an example) and low-melting-point (using copper as an example) anodes. The dependences of the main arc-discharge parameters on current density are presented. It is demonstrated that intense evaporation of particles of the anode material into the discharge gap occurs upon reaching the melting point of the anode surface. As a result, the plasma-forming ion is replaced, i.e., the carbon ion in the case of the graphite anode or a copper ion in the case of the copper anode becomes dominant. In the process, a jump in the potential is observed in the dependence of voltage on current density (the volt–ampere characteristic, VAC). Distribution of the main plasma parameters along the discharge gap is presented for different points in the VAC.

Three-dimensional plasma-dust formations consisting of calibrated dust particles differing in sizes and material densities are studied. The characteristic features of the structures formation in stratified glow discharge were studied, as well as their shapes and dynamics in the external magnetic fields. From several types of powders, the spatially separated double structures were obtained, which filled the dust trap, being located in different stratum phases. For each part of the structure, the average rotational velocities were obtained as functions of the magnetic field. In the range, in which the rotation mechanism depends on the particle size and the ion drag force is dominant, the rotational velocity was numerically estimated with allowance for the parameters variation along the stratum.

The exosphere of Mercury, which has much in common with the exosphere of the Moon, can also contain suspended dust particles, which, under the action of intense solar radiation, acquire positive charges and form one of the components of the dusty plasma system. In addition to dust particles, there are photoelectrons above the planet surface, formed as a result of interaction of solar radiation with the planet surface, as well as with suspended dust particles. Mercury, unlike the Moon, has its own magnetosphere, which affects the parameters of dusty plasma system. The dusty plasma parameters near the Mercury surface can vary depending on the distance from the planet to the Sun, which considerably changes when the planet moves along the elongated orbit, and also depending on the localization of the region under consideration on the planet surface. Thus, near the magnetic poles, the solar wind can reach the planet surface, which must be taken into account when determining the plasma parameters. Far from the magnetic poles, the effect of the solar wind can be neglected. In the dusty plasma near the surface of Mercury, one can expect the development of linear and nonlinear wave processes. In this paper, nonlinear waves are considered, namely, dust acoustic solitons and nonlinear periodic waves. The profiles of potentials of high-amplitude solitons and nonlinear periodic waves are obtained, as well as the soliton amplitudes as functions of the altitude above the planet surface and soliton velocity.

The semiempirical quasi-classical method of approximation of the ionization potentials used earlier for multiply charged ions of the elements with medium and high atomic number Z is applied to ions of elements with atomic numbers in the range of 85*z*110 and number of electrons in the range of 1*Ne*78. The discovered simple trends allow using a relatively accurate (to within 1–2%), based on two small tables, polynomial approximation of the available and lacking data on the ionization potentials in the NIST tables for all multiply charged ions in the atomic-number range under consideration. An improvement in the applicability conditions of the quasi-classical approximation with increase in the atomic number is demonstrated

The results of an experimental study of the initiation, development and maintenance of a plasma surface discharge initiated by microwave (microwave) radiation of a gyrotron (75 GHz, 300 kW, 6 ms) in air under normal conditions on the surface of a quartz substrate with metal inclusions are presented. It is shown that the velocity of the propagation of the discharge ionization front reaches 40 m/s, which corresponds to the thermal conduction propagation mechanism. In this case, the maximum calculated gas temperature of the plasma reaches 5500 K, which leads to the sublimation of metal inclusions. For the first time, the plasma parameters of a surface microwave discharge on metal-dielectric targets, which have been used in various aeroplasma and plasma-chemical applications, are presented.

A quantitative method for interpreting the spectroscopy signal of elastically reflected electron peaks is constructed taking into account the layer-by-layer analysis of the content of hydrogen isotopes in structural materials used in the international experimental thermonuclear reactor ITER under construction. The relative protium and deuterium concentrations in hydrocarbon samples are determined. The relative deuterium concentrations in a beryllium sample are determined.

Дан обзор новых наиболее интересных результатов, представленных на юбилейной L Международной Звенигородской конференции по физике плазмы и управляемому термоядерному синтезу, состоявшейся с 20 по 24 марта 2023 г. в Звенигороде Московской области. Проведен анализ достижений в основных направлениях развития исследований в области физики плазмы в России и их сравнение с работами за рубежом.