A relation between the mean average energy of accelerated ions epsilon i and the maximum rate of current rise in a vacuum discharge is established. The relationship takes the power form epsilon i varies as i1.3 for different ion species over a wide range of discharge parameters for i>i0=3*108 A s-1. For smaller values of i the corresponding value of epsilon i is almost independent of the discharge parameters. The ion mass and charge-dependence of epsilon i are also discussed.

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The travel of plasma flow produced by a dc arc through a transport system based on a curved magnetic field was studied. The characteristics of the system were the absence of a curved metallic plasma guiding duct ('open architecture') and the fact that the magnetic field coils were non-coaxial to the plasma flow. By means of Langmuir probe measurements it was shown that both shape and position of the cathode plasma flow at the exit of the transport system were governed by variation of currents of the magnetic coils as well as by biasing of a special electrode inserted into the plasma flow. It was found that with parameters of the transport system held constant, the plasma ions with lower m/Z were deflected more, e.g. Al ions were deflected more than Ti ions. For an arc with a composite cathode, consisting of mainly Cr-Fe-Ni, the profile of atoms of these elements at the exit of the transport system was measured by x-ray fluorescence spectrometry. The results obtained were consistent with the probe measurements, hence the transport system, in principle, may be used for spatial separation of a multi-component (in masses) plasma flow.

Ion parameters in a cathode plasma jet of a vacuum spark with a discharge energy of a few joules were measured. The studies were performed by a time-of-flight method with the help of an energy analyser. It was found that the discharge plasma generated a short-run beam of multiply charged ions of the cathode material at the initial stage of the discharge firing. The ions had charge states from Z = + 1 up to Z = + 18. When the initial capacitor voltage was varied within the ranges of 0.3-2.5 kV, the mean ion charge increased from +4.3 to +9.0.