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The plasma pinch on the basis of a gas jet with special density distribution is described. The gas jet was produced by means of a pulse gas valve with a nozzle that was capable of forming a gas flow with a maximum density in the center of the discharge gap. The diagnostic techniques involved measurements of the discharge current and the pinch voltage, the size of the radiation area and the X-ray intensity. The experiments with different gases (Ar, Ne and N2) showed that as a result of the discharge at this gas distribution the hot plasma area of "point" form (its typical size is 100 µm and lifetime 3-5 ns) arises in the middle of the discharge gap. This area is the X-ray source of energy of quanta 50-5000 eV. The radiation spectrum depends on the gas type. The experimental results are presented. [ABSTRACT FROM AUTHOR]

The results of the experiments on Z-pinch produced from wire arrays performed on the facility Angara-5-1 are presented. The models of liner implosion, i.e. prolonged plasma production have found their confirmation. Estimation based on our experimental data show that W wire cores are heterogeneous. The velocity of core expansion is determined by energy deposited at the first nanoseconds after current start. The effect of the inner array on the current distribution in the region between the arrays has been revealed. The «lost mass » was measured at initial radius of array at the moment of X-ray pulse maximum. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The results of the investigations into polarization of line radiation of multiple charged ion plasma of high-current Z-pinches are presented in the work. The experiments were performed on the ≪Angara-5-1≫ facility at Z-pinch currents of 2.5 to 3.5 MA. A dense high temperature pinch was produced by compresson of a hollow Ar gas jet injected by an electromagnetic valve with a supersonic nozzle. In the process of pinch compression the following plasma parameters have been achieved: electron density ne∼1021 cm−3 and electron temperature Te∼1 keV. The radiation spectrum was measured by use of a crystal spectrograph where mica (2d=19.8 A) served as a dispersive element. The spectrum of He-like ion of Ar was detected in reflection orders II and III. On the basis of the measurements performed the conclusions on the polarization degree of plasma radiation have been drawn. The work has been supported by Grant RFBR # 02-02-16832. [ABSTRACT FROM PUBLISHER]

Spectral characterictics of plasma radiation of a gas Z-pinch with a rise time of 1 µs and current amplitude of 250 kA have been measured. The measurements were performed in the range of X-ray energy quanta from 30 eV to 600 eV. A spectrograph with a transmission grating and a polychromator on the basis of multilayer X-ray mirrors served as the diagnostic devices. Absolutely calibrated semiconducing detectors AXUV-5 were taken as the radiation detector in the polychromator. Full pinch radiation loss was measured with a thermocouple calorimeter. The radiation of He-, Li- and Be- like ions has been shown to dominate at the stage of maximum compression of the nitrogen Z-pinch. The results of the spectral measurements were employed for absolute calibration of various X-ray detectors. Some of these calibration results are presented in the work. Using Ne and Ar as the working gases permits us to proceed to measurements in a ≪harder≫ spectral band and to conduct a detailed study of the line radiation polarization degree for He- like ions of the given elements. The work has been supported by Grant RFBR # 02-02-16832. [ABSTRACT FROM PUBLISHER]

Measurements of spatial shape of wire array produced Z-pinch is described. Nonsymmetry of the cathode and anode regions of pinch was observed. According to different spectra of X-ray emission emissive aria separates on two zones. For a single array an analogue of a ≪zipper effect≫ is observed: a hot zone appears at the cathode and expands towards the anode. [ABSTRACT FROM PUBLISHER]