PHYSICAL-PROPERTIES OF DENSE, LOW-TEMPERATURE PLASMAS

Plasmas occur in a wide range of the density-temperature plane. The ph ysical quantities can be expressed by Green's functions which are eval uated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, s tructure factor and local-field corrections, formation and decay of bo und states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization funct ion. The general model of a partially ionized plasma interpolates betw een low-density, nonmetallic systems such as atomic vapors and high-de nsity, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali -atom and mercury fluids. The occurrence of a metal-nonmetal transitio n near the critical point of the liquid-vapor phase transition leads i n these materials to characteristic deviations from the behavior of no nconducting fluids such as the inert gases. Therefore, a unified appro ach is needed to describe the drastic changes of the electronic proper ties as well as the variation of the physical properties with the dens ity. Similar results are obtained for the hypothetical plasma phase tr ansition in hydrogen plasma. The transport coefficients (electrical an d thermal conductivity, thermopower) are studied within linear respons e theory given here in the formulation of Zubarev which is valid for a rbitrary degeneracy and yields the transport coefficients for the limi ting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) a s well as degenerate, strongly coupled plasmas (Ziman theory). This li near response method is applied to partially ionized systems such as d ense, low-temperature plasmas. Here, the conductivity changes from non metallic values up to those typical for plasmas in a narrow density ra nge above 10(20) cm(-3) for alkali-atom plasmas and 10(22) cm(-3) for hydrogen plasma, respectively. Furthermore, the thermopower can change its sign in the same region which indicates that a nonmetal-to-metal transition occurs also in dense, low-temperature plasmas. The magnetic susceptibility and the Korringa relation are calculated for expanded fluid metals along the coexistence line within the partially ionized p lasma model. The various contributions to the total susceptibility are derived from an extended RPA which takes into account local-field cor rections as well as the influence of localized electron states. The me tal-nonmetal transition indicated by an enhancement of the electronic paramagnetic volume susceptibility is strongly connected with the occu rrence of charged clusters. Static structure factors an determined for expanded cesium and mercury within the MHNC scheme via effective ion- ion potentials which are derived from the polarization function within an extended RPA. The optical properties of dense plasmas, the shift a nd broadening of spectral lines, can also be derived within the Green' s function technique. Some new results for the spectral line shape are discussed.