Vol 50, No 9 (2024)

Comparative analysis of time evolutions of plasma macro- and microparameters during spontaneousand induced transient processes in the classical quasi-stationary stellarator L-2M is presented. Plasmaheating was performed in the electron cyclotron resonance heating (ECRH) regime at the second harmonicof electron gyrofrequency under conditions of high specific energy input in the power range of0.8−2MW/m3. Spontaneous transient processes are observed at constant heating powers, and induced onesare initiated by a stepwise increase or decrease in heating power. Correlation between time evolutions ofplasma macroparameters (primarily the energy lifetime) and the parameters of plasma turbulence is searched.Physical models of the phenomena that determine dynamic changes in plasma macroparameters are presented.Analysis of the data of high-frequency diagnostics made it possible to clear up the action of MHD andkinetic instabilities on transient processes in the stellarator hot plasma, as well as the role of plasma-wallinteraction.

The work provides an overview of the functional dependencies (formulas) for describing the properties of atomic particles sputtered during ion bombardment of the surface of a solid body. The dependence of sputtering coefficients on the energy and angle of incidence of the bombarding particle is considered. The energy spectra and average energies of sputtered particles are presented. Using the example of a target made of tungsten and hydrogen isotopes as projectiles, formulas for calculating the quantities under consideration are proposed. These data are necessary to estimate the entry of sputtered tungsten atoms as an impurity into a hot plasma using transport codes. When the tungsten impurity concentration is more than critical, it is impossible to carry out a controlled thermonuclear reaction with the planned energy output in the ITER tokamak reactor. Sputtering coefficients also play an important role in modeling the entry of impurities into plasma installations as a result of the interaction of hydrogen fuel atoms with the materials of the divertor and the first wall.

The paper presents the results of many years of research carried out in various organizations of theUSSR and Russia in the process of developing thrusters with anode layer (TALs) and stationary plasmathrusters (SPTs). They are known under the general name “thrusters with closed electron drift” (TCEDs),since they are developed on the basis of plasma ion accelerators with closed electron drift (ACEDs). TCEDshave come a long way in development. As a result, the SPT has become one of the most widely used electricrocket thrusters (ERTs) and continues to develop. The TAL development has also reached a fairly high leveland is close to practical use. Therefore, here we consider the main physical principles and research results thatdetermined the progress in the SPT and TAL development with the aim of their analysis and generalization,as well as assessment of their applicability for further development such thrusters. A brief overview of the mainstages of the SPT and TAL development and the results achieved at these stages are given. It is shown that themain problem of their further development is to ensure both high thrust efficiency and a long service life. Itis also shown that the main factor limiting the service life of TALs and SPTs is the ingress of accelerated ionsonto their structure elements; therefore, in order to control the ion motion, it is first of all necessary to understandthe patterns of electric field formation in TCED discharges. New properties of TCED discharges andthe peculiarities of electric field formation are revealed and their known properties are clarified, which determinethe thickness and position of the acceleration zone with the main potential drop in the discharge andthe flows of accelerated ions onto the thruster structure elements. The methods of controlling the thicknessand position of the acceleration zone in an TCED by varying the magnetic field characteristics, successfullytested at the second stage of the SPT and TAL development, are considered and analyzed. It is shown thatthese methods make it possible to effectively control the operation of an TCED and its characteristics, andphysical conditions ensuring the efficiency of their application are determined. Physical conditions for theimplementation and justification of the feasibility of completely removing the acceleration zone from the thruster as the main direction of modern TCED development are determined, taking into account the analysis of the properties of the discharge and the peculiarities of electric field formation in an TCED. The main conclusions on the issues considered are given.

Ion cyclotron resonance heating is considered as one of the methods of additional heating ofplasma and production of the non-inductive current in the T-15MD tokamak. To transfer the maximumpower to the plasma, it is needed to know impedance of an antenna–plasma system, to match it with impedanceof an RF power generator and its transmission line. The work is devoted to the development of a codefor the calculation of antenna impedance of the ICR heating system of plasma in toroidal magnetic traps. Tofind impedance of the antenna–plasma system in the simplified geometry of antenna consisting of conductiveplates, the wave equation is solved in the “cold” plasma approximation, and the spectrum of theRF power emitted by antenna is calculated. The dependences of the impedance of the antenna–plasma systemon distances between antenna and the Faraday screen and between the Faraday screen and the plasmaare obtained for the geometry of the T-15MD tokamak. Two-dimensional distribution of electric field of awave in the plasma is obtained.

Probe diagnostics of ion energy distribution and ion current density in the plasma plume of electricpropulsion is considered. A detailed numerical and experimental comparison is presented of a new, highdynamic range retarding potential analyzer (HDR RPA) and a conventional gridded RPA probe applied to aplume of a hall effect thruster (HET) operating in different modes. Simulations show the disadvantages of thegridded retarding potential analyzer design and the advantages of the HDR RPA. By means of numericalmodeling, the peculiarities of using the HDR RPA are also investigated in detail and preliminary conclusionsregarding the probe accuracy are drawn. The final part of the paper shows the results of joint tests of the twoprobes at those plasma parameters where the gridded probe works most accurately, with a confirmed maximumerror of 5%.

A theory of large-scale flows of rotating partially ionized space and astrophysical plasma in the approximation of the Hall magnetohydrodynamics is developed. Partially ionized rotating plasma describes large-scale processes in the exoplanetary atmospheres of hot Jupiters, the thermospheric–ionospheric system of planets and the Earth, in the protoplanetary disks, along with many other objects of heliophysics and space physics. The derived equations contain nontrivial terms describing the influence of rotation on the Hall current and ambipolar plasma diffusion in addition to the traditional Coriolis force acting upon momentum of the plasma’s center of mass. Linear flows are analyzed in the simplest case when gravity is neglected. The dispersion relations for modified Alfv.n waves, rotating fast and slow acoustic waves, along with modified whistler waves, are obtained. The slow acoustic waves represent a new type of flows driven by the Coriolis force. The fast acoustic waves correspond to conventional acoustic waves in the absence of rotation.