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The possibility of creating adjustable electric fields in plasma opens up a wide range of applications for plasma technologies. However, the question with regards to the conditions, under which the plasma potential along the magnetic field line, resting on the electrode, repeats the potential of this electrode, turns out to be quite complex. In the present paper, an axially symmetric system with a magnetic field directed along an axis is considered. At the ends of the system, there are electrodes with a given negative potential. A simplified model of the system is proposed, taking into account the near-electrode voltage drop and continuity of the current in the circuit of the end electrodes. Within the framework of this model, an analytical formula is derived for the plasma potential on the axis of such a system, depending on its parameters. This formula can serve as a guide for experimenters when choosing experiment parameters, the purpose of which are to create a negative radial electric field in plasma. The data, obtained using the proposed model, are compared with existing experiments, and their agreement is demonstrated.

The details of the charged particle separation by mass in the configuration with axial magnetic and radial electric fields are studied. The radial electric field, oriented to the discharge axis, is induced in a background reflex discharge with a hot cathode (−550 V, 8–14 A). The plasma source is based on a hot cathode arc discharge with independent metal vapor injection (18–21 V, 30 A) was situated at 18 cm from the axis. It was shown that the separated Ag + Pb mixture is transported across the magnetic field under the background discharge electric field. Effective separation is possible in such a system, while the separation coefficient increases from 4.9 to 6.2–8.4 when the mixture injection point is moved away from the background discharge axis from 18 to 23 cm. The effect of mixture injection on the plasma potential distribution is examined. It was shown that the presence of a plasma source of separated substances can cause a local (1–2 cm) distortion of the background plasma potential profile. Such distortion, as well as fluctuations of the background plasma potential, can significantly affect the width of the deposited spots of separated substances.

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The possibility of controlling the electrostatic field distribution in plasma has yielded wide prospects for modern technologies. As a magnetic field primarily allows for creating electric fields in plasma, it serves as an additional obstacle for the current flow through a medium. In the present paper, an axially symmetric system is considered in which the magnetic field is directed along the axis and concentric electrodes are located at the ends. The electrodes are negatively biased. A model which solves the problem of the radial distribution of the plasma potential inside the cylindrical plasma column supported by the end electrodes is proposed. The most commonly encountered configurations of the electrical connection for the end electrodes are considered, and the particular solutions to the problem of the radial distribution are presented. The contribution of ions and electrons to the transverse conductivity is evaluated in detail. The influence of a thermionic element on the radial profile of the plasma potential is considered. To verify the proposed model, an experimental study of the reflex discharge is carried out with both cold electrodes and a thermionic element on the axis. A comparison of the computational model results with experimental data is given. The presented model makes it possible to solve the problem concerning the plasma potential distribution in the case of an arbitrary number of end electrodes, and also to take into account the inhomogeneity of the distribution of plasma density, neutral gas pressure and electron temperature along the radius.

The problem of generating a stationary electric field in a magnetized radio-frequency discharge (rf) plasma is studied experimentally. Helmholtz coils produce magnetic field in a cylindrical vacuum chamber with diameter of 85.6 cm and length of 220 cm. RF discharge is generated at a frequency of ∼ 5 MHz. The rf power absorbed by plasma lies in the range 0.5-1.5 kW. Electrodes defining a negative potential are placed at the ends of the chamber. Two pairs of circular flat electrodes with diameter of 5.5 and 45 cm are investigated. The working gas is argon. Radial profiles of electron density and temperature are obtained. Radial profile of the plasma potential is investigated, as well as the dependence of plasma potential on the voltage applied to the end-electrodes.