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.
The electrical conductivity of carbon plasmas is measured in the range of densities from about 0.6 solid density down to about 0.05 solid density, and reported for values of internal energy ranging from 2 to 22 kJ/gm . Plasmas are formed by rapid electrical discharge through thin graphite fibers immersed in a water bath. The pressure in the expanding plasma column is determined by use of a hydrodynamic model to describe the effect on the water surround. It is found that at constant internal energy per unit mass U, conductivity sigma varies with specific volume v as sigma = v(-alpha), where alpha is about 1 for U < 6 kJ gm , and rises to about 1.5 for U = 22 kJ gm .
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An amorphous phase of Co3BTCA2(H2O)6 has been prepared (BTCA=1,3,5-benzenetri- carboxylate). The static properties (dc susceptibility, hysteresis) of Co3BTCA2(H2O)6 are similar to those of other ‘‘glassy’’ magnetic systems, but the dynamics of Co3BTCA2(H2O)6 (absence of long relaxation times, disappearance of frequency dependence at low temperatures) are unusual. The amorphous phase is characterized by a narrow hysteresis loop at low temperature. For the hysteresis curve at 4.2 K, the coercive field is several hundred Oersted and the remnant magnetization is on the order of 10−2 Msat. The temperature dependence of the dc magnetic susceptibility shows an unusual field dependence below 30 K, with the largest effective moments being obtained in the smallest applied fields. The freezing temperature, Tf, in zero field, as determined by both dc and ac susceptibilities, has been found to be Tf=23 K. The ac susceptibility shows the characteristic spin glass frequency dependence, yet loses all frequency dependence for temperatures below 9 K.
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SUPPLEMENTARY NOTES* Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742
ABSTRACTThe electrical conductivity of carbon plasmas is measured in the range of densities from 0.16 solid density down to about 0.05 solid density and reported for values of internal energy ranging from 4 to 22 kJ/g. Plasmas are formed by rapid electrical discharge through thin graphite fibers immersed in a water bath. The pressure in the expanding plasma column is determined by a hydrodynamic model to describe the effect on the water surround. At constant internal energy per unit mass U, conductivity σ varies with specific volume V as σ = V α , where α is about 1.2 for U 6 kJ/g < , and rises to about 1.5 for U = 22 kJ/g.
SUBJECT TERMSplasma, electrical conductivity, carbon, energy, temperature
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