Photoelectric spectra of the regions corresponding to resonance line emission of He-like ions of titanium, iron, and copper from a low-inductance vacuum spark were obtained, as were spectra of the regions corresponding to Ea and KP emission from the same elements and to XP emission of molybdenum. Electron temperatures are estimated from continuous x-ray emission spectra to v T, 5 15 keV; ion temperatures from x-ray line widths to v T, -10 keV. A broad peak superimposed on the visible continuum is interpreted as anomalous bremsstrahlung at twice the electron plasma frequency. The resultant electron density is N, = 5 X 10' cm ', consistent with the absence of forbidden He-like ion lines. Experimental observations support the suggestion that the x-ray-producing dense plasmas are due to interactions between pulsed electron beams and lowtemperature anode vapors or plasmas.

At plasma densities lower than about 1018 cm-3, strictly speaking, the LTE model cannot be used when the electron temperature is calculated from measured spectral line intensity ratios. In this work a number of nitrogen spectral lines were studied at an electron density of about 1016 cm-3, and the results are discussed with reference to the LTE and semi-coronal models. A method is suggested for analyzing line intensity ratio data from plasmas in the semi-coronal regime.

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The behavior of a hydrogen plasma inside a coil which gives a vacuum magnetic field with minimum |B| properties, has been studied in some detail. Streak and framing pictures were taken and the variation of electron density with time was measured. During the first half-cycle of the coil current, the plasma appeared to be stable. The experiment were carried out at relatively low energy. For purposes of comparison, a theta pinch was studied using the same capacitor bank.

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