Abstract. The production of NO has been studied by means of arc discharges in the laboratory which simulate natural lightning in current waveform and amplitude (___ 30kA). Observations are compared to the results of a computational model that includes the dynamics of energy deposition and channel expansion, combined with the Zel'dovich equations to model the relevant chemical reactions. Results are expressed as NO produced per meter of arc length, and are measured as functions of dissipated energy and of peak current. It is found that at atmospheric pressure, the NO production per joule of dissipated energy is not constant. NO production per meter discharge length as a function of peak current appears to provide a more

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We report measurements of electrical conductivity of eight metals in the plasma state at densities ranging from 0.002 to 0.5 times solid density, and with internal energy from 2 to 30 kJ/gm. Data are presented as functions of internal energy and specific volume. Conductivity is observed to fall as the plasma expands for fixed internal energy, and for all but tantalum and titanium shows a minimum at approximately 0.01 times solid density, followed by an increase as the density decreases further.

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Progress in the exploding wire techniques for the measurements of the electrical conductivity of dense metal plasmas is reviewed. It is demonstrated that the data on the conductivity obtained by means of quite different techniques give results in good agreement. Recent results of direct measurements of the conductivity, internal energy and density of tungsten over a wide density and temperature ranges are presented. It is speculated that the data may lead to improvements in the conductivity and EOS databases. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Spatially resolved measurements of the magnetic field of a spheromak have been analyzed and compared with expectations for the ratio of j\\/B from the pre s sure-gradientfree Taylor model and a model with pressure due to Morikawa. Better agreement is found with the model containing finite pressure.

In diagnosing the Maryland Centrifugal Experiment (MCX) [R. F. Ellis et al., Phys. of Plasmas 8, 2057 (2001)], earlier spectroscopic measurements of averaged plasma rotation velocities have been upgraded to include radial distributions, using a five-channel fiber-optic collection system. Detailed information from each view is now possible with an 8-times increase in spectral resolution, by using a 2m spectrograph and a 2400lines∕mm grating. Inversion of the integrated chordal radiation into a radial dependence of local emissions is performed by two methods: (a) an iterative simulation beginning with assumed emissions in five axially concentric cylindrical zones followed by summation along the five viewing chords, and (b) inversion of a combination of dual Abel-type matrices. The radial profiles of the absolute velocities derived cover a range from 20to70km∕s for both C+ and C++ impurity ions. Previous apparent differences in velocities between ions from a single chordal observation are now explained by the measured radial dependence of velocities and relative emissions. An important result is the first direct and quantitative measurement on MCX of a radial shear in rotational flow velocity as large as 9×105s−1, 9 times a threshold of 1×105s−1 for magnetohydrodynamic stability. Stark-broadened hydrogen Balmer-series spectral lines provide both a value for electron density of Ne=(8.5±1.5)1014cm−3 and supporting data for radial particle distributions.