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Line emission from highly charged ions in the soft x-ray region represents an important diagnostic for high-temperature plasmas. The wavelength region of 10–30 Å is occupied by lines from the K-shell transitions in N through Ne and L-shell transitions in Ti through Ni. Crystal spectrometers have previously been used to investigate Fe line radiation under well controlled conditions using the LLNL electron beam ion trap facility in this wavelength region. To complement this work we have instituted a grazing-incidence spectrometer with a variable line-spaced, concave grating and a flat field of focus which is suited for a multichannel detector. Simultaneous observations of the Ne-like Fe16+ n=3→2 transitions were made with this instrument and a flat-crystal spectrometer in order to establish the linear polarization of the Fe XVII lines. We present a description of the grating spectrometer and discuss its performance in comparison with Rowland circle based grazing incidence instruments.

Experiments with small magnetic probes suitable for advanced undergraduates are described. The experiments are designed to show that an inductive probe does not respond to high-frequency signals (1–70 MHz) as might be expected from experience with probes at low frequencies. Pickup of noninductive signals is demonstrated, resonances are observed, and the inductance, capacitance, resistance, and effective area of the probe are measured. In addition, the conductivity of copper and aluminum is found using thin metal foils.

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A possible mechanism is discussed for the hard-x-ray emission observed in vacuum spark plasmas. The mechanism is based on the hypothesis that in the process of a sausage instability in a plasma pinch the plasma can have very high resistivity due to the constriction and strong turbulence, so that the conduction current is virtually cut off. In such a case strong electric fields should appear which could accelerate the electrons and ions to produce hard x rays as energetic as 20 times the discharge potential. The kinetic energies of ions and electrons are calculated.

The size and shape of an x-ray source formed by a plasma pinch have been determined using time-integrated pinhole photography. Pinhole diameters as small as 4 μ have been used to image a source whose length is usually about one order of magnitude larger than this pinhole diameter. Such measurements should refine the density determination of the source and are essential to specifying a charged-particle acceleration mechanism in the pinch region. The x-ray images, visible streak photographs, and x-ray-source lifetime measurements suggest that the x-ray source may, as a whole, be moving as it emits.

Using both the LLNL high-voltage electron beam ion trap, SuperEBIT, and its low-energy counterpart, EBIT-II, we are currently performing spectroscopic measurements with electron beam energies ranging from 150 eV to 150 keV on ions ranging from near neutral Ne to ions as highly charged as Tl 80. Our measurements span photon energies from visible light to hard X-rays and focus on electron-ion interaction cross sections, line identi¢cations and QED measurements, the determination of nuclear parameters, the investigation of charge transfer reactions, and radiative transition rates. An overview of some of the new instrumentation and a subset of the current experiments is given.