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[en] Experimental results of tearing instability investigation at T-13 tokamak are given. Instability was observed under such conditions, when plasma filament could move freely along a large radius. Multichannel measuring system ''Sapphire-2'', comprising a microcomputer, multichannel digital recorder, recorder on the base of multichannel device for accurate magnetic recording, was used for data ecquisition and for accumulation and archiving of experimental data

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[en] Characteristics of low frequency (LF) oscillations of low density plasma νsub(pi) <= νsub(ci) where νsub(pi) and νsub(ci) are ion plasma and cyclotron frequencies, respectively, have been experimentally investigated. Experiments were carried out in the ''Ogra-3B'' simple mirror. LF-oscillations of 1-500 kHz were recorded by electrostatic antennas (including mobile ones) located near plasma surface. The antennas allowed to measure the mode structure and oscillation amplitude out of plasma. To measure oscillation characteristics in plasma cold ion and electron flux fluctuations behind the mirrors along line of force have been recorded. The experiments carried out show that intensive LF-oscillations may be excited in open traps with minimum B. LF-oscillation generation is accounted for within the frames of a simple model of plasma column natural forced flute oscillations. The waves are excited by injected beam current fluctuations at density below the threshold of high-frequency (HF) oscillation origination and by HF-oscillations at higher densities near cyclotron frequencies

[en] An MHD diagnostic system for investigating the dynamics of disruption and the preceding phase of the discharge in the T-11M tokamak is described. This system makes it possible to study the structure of magnetic fluctuations in the plasma column. The diagnostic system includes a set of magnetic pick-up loops (Mirnov coils) arranged in several poloidal cross sections of the tokamak, a data acquisition system that provides synchronous recording of Mirnov coil signals, a synchronization system for triggering the data acquisition system during a disruption, and a system for processing and representation of the experimental data on magnetic fluctuations in the plasma column. Examples of how the MHD diagnostic system operates in the T-11M tokamak are presented

[en] The MHD-diagnostics complex, created at the T-11M tokamak for studying the break-away development dynamics in the preceding discharge phase, is presented. The above complex provides for the study on the structure of the plasma filament magnetic fluctuations. The complex consists of the set of the point magnetic probes, located in several poloidal cross sections of the torus; the data acquisition system, providing for the synchronous registration of the point magnetic probes signals; the synchronization system, providing for the data acquisition system initiation by the break-away registration; the system for processing and presenting the results of the plasma filament magnetic fluctuations registration. The examples of the MHD-diagnostic complex operation at the T-11M tokamak are presented

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No abstract available