[en] The merging of current filaments formed as a result of the tearing-mode instability of the current sheet in the plasma of a theta pinch has been studied experimentally. Ohmic dissipation of the current in the filament is observed to increase during the merging. The merging rate is controlled by the level of small-scale turbulence in the sheet, which determines the necessary values of the anomalous conductivity and thermal conductivity

[en] The magnetic-structure evolution and the spatial energy distribution of the electrons of a current sheet in a theta-pinch plasma are investigated. It is shown that in the initial stage of the reconnection the energy release is via uniform ohmic current dissipation causing a flareup heating of the electrons. The evolution of the reconnection leads to formation of magnetic islands, i.e., to current concentration and to current fibers with dense highly conducting plasma, where the ohmic dissipation is turned off. The energy release is localized in the islands, into which the field energy flows in with the plasma, and in which it is released via hydrodynamic motions into the ionic component. High-energy electrons are observed in the vicinity of the O point during this stage

[en] A parameter which controls the change in the magnetic structure of a current sheet has been found experimentally. When the value of this parameter is below a threshold, the magnetic islands that arise during the onset of the tearing-mode instability move away from each other. In the opposite case, the islands coalesce, with the result that an extended current sheet is converted into a current filament

[en] It is shown that the process of ion acceleration in the plasma jet of a vacuum arc can be explained by entrainment of ions by the electron flux moving from the cathode toward the anode. The frictional force has a turbulent nature, due to the buildup of ion-acoustic turbulence by the current. A similar mechanism may also occur in a current-carrying plasma jet generated in the polar region of the magnetosphere, resulting in the observed energies of accelerated O⁺ ions

[en] A pinhole camera for the soft-x-ray range (0.2--10 keV) with a microchannel-plate detector has been developed. The construction and basic characteristics of this camera are reported. The spatial resolution of the detector is 20 lines/mm. The brightness intensification, the trigger time, and the duration of the exposure are all set by a pulse from the power supply for the microchannel plate. The capabilities of the camera are demonstrated in experiments with a turbulent neutral current sheet. Analysis of an image produced by electron bombardment of a special target in the plasma reveals an electron current in the plasma with a current velocity of 0.3v_Te. The plasma density is n> or =10¹² cm^-3, the electron temperature is T_e> or =0.2 keV, and the exposure time is 200 ns

[en] The formation of a neck in the cathode plasma jet in the initial stage of a low-voltage vacuum spark is investigated experimentally and theoretically. X-ray bursts corresponding to an electron temperature of 150-300 eV are detected. With the use of a pinhole camera, it is found that an emitting region less than 1 mm in size is located near the cathode. The free expansion of a current-carrying cathode plasma jet with a current growing in accordance with the experimentally observed time dependence is simulated using a hydrodynamic model. It is shown that the neck forms at the front of the plasma jet due to the plasma compression by the magnetic self-field. In the constriction region, the plasma is rapidly heated and multiply charged ions are generated. The calculated spatial and temporal variations in the electron temperature and average ion charge are close to the measured dependences over a wide range of the discharge parameters