Electric Microfield Distributions

Abstract

Recent research on controlled fusion by inertial confinement has stimulated renewed consideration of atomic phenomena in hot, dense plasmas. In many cases the dominant coupling of the atom to its plasma environment is through the atomic dipole interaction with the local electric microfield. The electric microfield distribution (probability density for a given field value) is therefore an important property of the plasma for description of such atomic processes as emission and absorption of radiation. Prior to laser-produced plasmas, typical laboratory experiments involved only weakly coupled plasmas and quite accurate theories were available to calculate the microfield distributions under such conditions1,2. These theories fail for strongly-coupled plasmas and present research has focused on calculations for more extreme plasma conditions. Progress in this direction was initiated by Iglesias, et. al.3,4 who proposed a method for ion fields at charged points, which gives excellent agreement with computer simulations of strongly coupled classical one component plasmas (OCP) in two and three dimensions. Extension of this method to multi-component plasmas also proved fruitful5. Subsequently, others have addressed related aspects of microfields in dense plasmas such as ion fields at neutral points, electron fields7, effects of atomic structure8, and quantum degeneracy9,10. The objective here is to review these developments in a general context, to clarify some of the approximations used, and to identify some of the remaining problems.