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Gas mixture system (GMS) was developed, created and installed at Uragan-2M (U-2M) device. GMS is based on already known gas mixing method  successive puffing. It is implemented through successive puffing of several gases from separate high pressure cylinders into working volume. A number of experiments were carried out to create a He+H2 gas mixture with different percentages. The results of measurements of the He+H2 percentage in the GMS and the U-2M vacuum chamber are in good agreement each to other. This system allows you to change the pressure of the mixture in the U-2M chamber at a constant percentage of gases in the mixture.

For the Uragan-2M stellarator, a glow discharge cleaning (GDC) system is developed. An overview of the GDC system design is presented. The first experimental studies of GDC in an argon atmosphere have been carried out. The dependence of the breakdown voltage on the argon pressure is determined. The current-voltage characteristics of the gas discharge were measured as a function of the working gas pressure also in presence of a magnetic field.

In support of the ICRF experiments planned on the Wendelstein 7-X (W7-X) stellarator, i.e. fast ion generation, wall conditioning, target plasma production and heating, a first experimental study on plasma production has been made in the Uragan-2M (U-2M) stellarator using W7-X-like two-strap antenna. In all the experiments, antenna monopole phasing was used. The W7-X-like antenna operation with launched radiofrequency power of ~100 kW have been performed in helium (p = (4–14) × 10−2 Pa) with the vacuum vessel walls pre-loaded with hydrogen. Production of plasma with a density higher than 1012 cm−3 was observed near the first harmonic of the hydrogen cyclotron frequency. Operation at first hydrogen harmonic is feasible in W7-X future ICRF experiments.

The results of experimental studies of the influence of runaway electrons on the parameters of the neutral gas breakdown and suppression of the runaway electron flow in the Uragan-2M torsatron are presented. The influence of the presence or absence of the runaway electron flow on the time characteristics of the breakdown is experimentally studied via comparative analysis. It is demonstrated that in the presence of the runaway electron flow the breakdown takes place earlier by an average of 1.5 ms, as compared to the breakdown in the absence of the runaway electron flow. This is also proved by the earlier results obtained at the Uragan-3M torsatron, which allows one to continue the description of some aspects of the runaway electron dynamics and its regularities and formulate a number of recommendations on controlling such electron flows in fusion installations.

In the l = 3 Uragan-3M torsatron hydrogen plasma is produced by RF fields in the Alfven range of frequencies (ω ≤ ωci). The initial (target) plasma with the line-averaged density of units 1012 cm−3 is produced by a frame antenna with a broad spectrum of generated parallel wavenumbers. After this, to heat the plasma and bring its density to ~1013 cm–3, another, shorter wavelength three-half-turn antenna with large transverse currents is used. The behavior of the density, electron temperature, and loss of the plasma supported by the three-half-turn antenna is studied depending on the RF power fed to the antenna and initial values of the density and electron temperature supplied by the frame antenna.

A method for cleaning vacuum surfaces by a low-temperature (Te ∼ 10 eV) relatively dense (ne ≈ 1012 cm−3) plasma of an RF discharge was developed and successfully applied at the Uragan-3M torsatron. The convenience of the method is that it can be implemented with the same antenna system and RF generators that are used to produce and heat the plasma in the operating mode and does not require retuning the frequencies of the antennas and RF generators. The RF discharge has a high efficiency from the standpoint of cleaning vacuum surfaces. After performing a series of cleanings by the low-temperature RF discharge plasma (about 20000 pulses), (i) the intensity of the CIII impurity line was substantially reduced, (ii) a quasi-steady operating mode with a duration of up to 50 ms, a plasma density of ne ≈ 1012 cm−3, and an electron temperature of up to Te ∼ 1 keV was achieved, and (iii) mass spectrometric analysis of the residual gas in the chamber indicated a significant reduction in the impurity content.

Recent results of the experimental program on the stellarator-type device Uragan-3M at the IPP in Kharkov are presented. Efforts were focused mainly on optimization of the operation of the frame-type radiofrequency antenna to produce a target plasma for the three-half-turn antenna. Different regimes of the Uragan-3M operation, which are characterized by different temporal behavior of the average plasma density, electron cyclotron emission radiation intensity and particle confinement time, are considered. Elementary atomic processes responsible for plasma creation are studied. The particle confinement time for the Uragan-3M plasmas is estimated. Measurements of energy spectra of charge exchange atoms are carried out. The principal possibility of realizing a 'stellarator–magnetic mirror' scheme as a prototype of a stellarator-mirror fusion–fission hybrid is shown for Uragan-2M. Future plans are discussed.

The very high frequency (VHF) discharge for wall conditioning with hydrogen atoms is studied. It is driven by the RF power at frequencies ∼140MHz, higher than usually used in ICRF. For wall conditioning a special small size antenna is designed. The antenna is aimed to excite the slow wave that is damped via electron collisions with neutral gas. The wave excitation is modelled using a 1D numerical code. In the experiment, the discharge parameters are studied as functions of confining magnetic field and gas pressure. The Langmuir probe measurements give the radial profiles of plasma density and electron temperature. The discharge is volumetric: plasma occupies whole confinement volume and even steps out at the edge. The characteristic value of plasma density is 10 10 cm −3 , electron temperature varies in the range 3‐10eV. The temperature values of probe measurements are compatible with the results of optical diagnostics. Such parameters of discharge are favourable for wall conditioning in hydrogen. The discharge parameters did not reveal any sensitive dependence on neutral gas pressure and the toroidal magnetic field. The mass spectrometry of the residual gas is used for monitoring the wall conditioning effect of the VHF discharge.