The effect of an axial magnetic field Bz on an imploding metallic gas-puff Z-pinch was studied using 2D time-gated visible self-emission imaging. Experiments were performed on the IMRI-5 generator (450 kA, 450 ns). The ambient field Bz was varied from 0.15 to 1.35 T. It was found that the initial density profile of a metallic gas-puff Z-pinch can be approximated by a power law. Time-gated images showed that the magneto-Rayleigh–Taylor instabilities were suppressed during the run-in phase both without axial magnetic field and with axial magnetic field. Helical instability structures were detected during the stagnation phase for Bz < 1.1 T. For Bz = 1.35 T, the pinch plasma boundary was observed to be stable in both run-in and stagnation phases. When a magnetic field of 0.3 T was applied to the pinch, the soft x-ray energy was about twice that generated without axial magnetic field, mostly due to longer dwell time at stagnation.

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The mass and charge composition of the plasma of a vacuum arc with thick and film type zirco nium cathodes containing deuterium and hydrogen is investigated experimentally and theoretically. For a thick cathode, it is shown that such a system ensures effective generation of deuterium ions with an integral fraction per arc current pulse of approximately 60%; the maximal concentration of deuterium is observed at the initial stage of the arc operation. In the case of the film cathode, such a concentration of hydrogen iso topes can be attained for currents exceeding 400 A and for an arc duration at a level of a few tens of microsec onds. Occlusion of deuterium in the cathode leads to additional energy expenditures for its ionization and, as a consequence, a decrease in the average charge of ions of the cathode material in the arc plasma. Deuterium in the cathode spot is ionized completely, and the drift velocity of its ions almost coincides with the velocity of ions of the cathode material due to the high frequency of ion-ion collisions in the cathode region. The inter action of a dense (~10 20 cm -3 ) cathode spot plasma with microinhomogeneities of the cathode surface leads to the development of thermal instability in them over time intervals that do not exceed tens of nanoseconds.

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An experimental and theoretical study of the content of deuterium ions in arc discharge plasma was performed for deuterated zirconium cathodes. It was found experimentally that the deuterium ion percentage increased significantly with increasing arc current and decreasing arc duration, reaching 85% at kiloampere currents and few microsecond durations. In this case, a clear correlation was found between the content of deuterium ions in the arc plasma and the mean charge of zirconium ions: the higher the mean Zr ion charge, the greater the amount of deuterium ions in the plasma. A model was developed to describe the ionization processes that occur in the plasma of a vacuum arc with a deuterated cathode. It was shown that the relative content of deuterium ions in the plasma jet ejected from an individual cathode spot cell is not over 50%. The deuterium atoms are additionally ionized when the plasma jets of individual cells are mixed within a group cathode spot with high average current density. Conditions for additional ionization arise when the density of cells on the cathode surface is high, that is, at the initial stage of the discharge operation.