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Kotenko V.G.,Institute of Plasma Physics of Ukraine
Problems of Atomic Science and Technology | Year: 2014

In numerical calculations for the model of combined magnetic system a possibility of existence of closed magnetic surfaces is shown. The model comprises the magnetic system of l=2 torsatron without additional toroidal magnetic field coils (heliotron) with a single current-carrying turn as an element of the mirror-type magnetic system. The turn encircles the heliotron closed magnetic surface region and produces a magnetic field of opposite direction to the heliotron magnetic field. © 2014, National Science Center, Kharkov Institute of Physics and Technology. All rights reserved. Source


Pavlichenko R.O.,Institute of Plasma Physics of Ukraine
Problems of Atomic Science and Technology | Year: 2014

A new electron cyclotron emission antenna was designed to be installed outside of Uragan-3M vacuum tank. The system will be utilizing different diagnostic port to minimize the length of the output microwave beam. Its design is based on Gaussian beam optics and consists of two plane and two concave mirrors. The concave mirror surfaces are defined using the concept of elliptical surface, where the origin of emission and outside detection antenna coincide with foci of ellipsoid. The new electron cyclotron emission antenna will be installed for a 2015 experiment to measure the electron temperature profile and its fluctuations. This paper reports the general design of the new quasi-optical antenna system. © 2014, National Science Center, Kharkov Institute of Physics and Technology. All rights reserved. Source


Dreval M.B.,Institute of Plasma Physics of Ukraine
Problems of Atomic Science and Technology | Year: 2014

A miniature pinhole camera array for spatially and temporally resolved measurements of soft X-ray emission has been designed and installed in the URAGAN-3M torsatron. Two features of the U-3M: a) very large vacuum vessel; b) a quite high RF noise from the 8-9 MHz plasma heating generators, form a rather difficult for the SXR system design conditions. In order to increase the SXR brightness in 25-50 times the pinhole camera is placed between helical coils near plasma in the “A-A” cross-section. The size of the pinhole and its location relative to the diode array are optimized to cover the whole poloidal cross section and to achieve a good spatial resolution with minimum overlap in nearby channels. Possible misalignments of the SXR system can cause errors in the line of sight impact parameter less than 30 (similar to the SXR channel viewing angle). The maximum of the measured SXR brightness intensity corresponds to the central channel № 11 of the system. The 2.5 107 V/A SXR photodiode photocurrent amplifiers with additional RF noise suppress electronics have been manufactured. The SXR electronics does successfully work in high vacuum conditions near the plasma. Time evolution of the SXR emission profile and its fluctuations are successfully measuring by the designed diagnostics. © 2014, National Science Center, Kharkov Institute of Physics and Technology. All rights reserved. Source


Dreval M.B.,Institute of Plasma Physics of Ukraine
Problems of Atomic Science and Technology | Year: 2015

A miniature pinhole camera array for spatially and temporally resolved measurements of soft X-ray plasma emission has been recently installed on the U-3M. The diagnostics has been tested in different types of the U-3M discharge. In low density frame antenna discharges with so-called “H-like” transition a fast SXR emission profile modification is observed. A phase shift of the SXR perturbation induced by the transition as well as different shapes of the perturbation is observed in different channels. The transition can be associated with MHD instability. Different shapes of the SXR emission profile has been observed in different discharge conditions. The SXR array is en excelent tool for study different types of the MHD activity. Different types of the low frequency MHD activity have been observed in the U-3M torsatron. The recently installed SXR diagnostics opens opportunity of detailed studies of the MHD activity together with its driver–the plasma pressure gradient. In the paper we are presented recent experimental results obtained with the use of SXP, without deep analysis these experiments. © 2015, National Science Center, Kharkov Institute of Physics and Technology. All rights reserved. Source


Yeliseyev Y.N.,Institute of Plasma Physics of Ukraine
Problems of Atomic Science and Technology | Year: 2015

The low-frequency spectrum of axially-symmetric modes of oscillations of the nonneutral plasma completely filling a waveguide is evaluated. Plasma consists of cold electrons and a small additive of ions produced by ioniza-tion of neutrals of background gas by electron impact. Ions are described by the equilibrium distribution function adequately taking into account the peculiarity of their formation. The spectrum of oscillations consists of the family of lower hybrid modes and families of "modified" of ion cyclotron (MIC) modes. MIC modes intersecting lower hybrid modes are unstable within a wide range of changing of fields and plasma density due to anisotropy of the ion distribution function. © 2015, National Science Center, Kharkov Institute of Physics and Technology. All rights reserved. Source

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