[en] Electron beams with high current density present a great interest for industrial and medical application because of its capacity to transport stored energy through rather long distance to the target objects without any noticeable losses. Besides, it is possible to control the beam parameters by means of external transporting conditions. In this work, the theoretical and experimental results due to additional external systems transporting investigation and focusing of electron beam propagation in the drift tube filled with plasma discharged at low pressure argon 10^-2 ∼ 10^-4 Torr were determined. The electrons movement equations in general case of nonuniform external field were analytically and numerically solved. It was obtained that the nonuniform of external magnetic field have noticeable role in transporting of electron beam. The experiments were conducted on several machines to determine the configuration influence of the magnetic field on compression (defocusing) of the beam. The experiments were realized also with application of two or three solenoids. The location of solenoids had been calculated theoretically. Experiments show possibility of compression of the beam, and increase in stability of the distribution of energy density on the irradiation area. The focusing of electron beam with initial angle speed spread tgΘ = v(perpendicular)/ v(parallel) = 0.26 (Θ ∼ 16^o) is shown. The radius of beam transporting envelope and longitudinal velocity of electrons essentially depends on the level of magnetic field gradient and the distance ratio between focuses and beam parameters. Changing of magnetic field can be governed by the energy density transferred to the beam collector. (author)

[en] Experimental study of high-frequence discharge in air with water vapor demonstrates that strong plasma cooling and anomalous increase of recombination time take place in this system. The high-frequency discharge in air at different pressures of gas and water vapor has been numerically investigated in the given paper. Simulation was carried out on the basis consistent solution of the equations of both particle balance and thermal one. Main reactions were being taken into consideration at that including origination and loss of positive and negative ions and water molecules breaking. The processes connected with water molecules vibration excitation and the processes of electrons dissociative -attachment to H₂O molecules are assumed to be the principal mechanism of plasma coo ling. The concentration of arising ions and the dependence of electron temperature on time, gas pressure and water concentration have been determined. The analysis of the discharge plasma recombination has been carried out. Numerical simulation results are in agreement with the experimental ones

[en] At present, the virtual cathode systems (vircators) are used for generation of powerful emission. One of peculiarities of the magneto-insulated diode vircator is the generation possibility on the two frequencies. In particular, it can be used for plasma heating of fusion plasmas. In present paper the two-frequency generation mechanism for increasing of emission efficiency and realizing of the emission parameters operating is investigated. The problem has been investigated by means analytical and numerical methods. It has been shown that two-frequency generation regime is conditioned by two virtual cathodes forming. In result, the nonsymmetrical potential well is formed in which the flow electrons are captured. It has obtained that the depth of the potential well and emission power are considerably higher for the foil system in comparison with foilless system. The dependencies of frequency spectrum and efficiency on system geometry and external magnetic field have been determined. It has been shown that the frequency spectrum and emission power do not depend on drift tube length if it exceeds the Debye radius calculated with taking into account the reduction coefficient. The influence of transverse impulse and velocity spread on efficiency are studied. Comparison of theoretical results with experiments is carried out

[en] Possibility of frequency control in vircators by means of beam parameters, magnetic field and external microwave signal has been studied. The conditions have been found when generated frequency doesn't depend on magnetic field B but radiation power has resonant dependence on B. It has been shown that some vircators can operate at two frequencies simultaneously