Nuclear reaction rates and energy in stellar plasmas: The effect of highlydamped modes

The effects of the highly damped modes in the energy and reaction rates in a plasma are discussed. These modes, with wave numbers k>>k(D), even being only weakly excited, with less than k(B)T per mode, make a significant cont ribution to the energy and screening in a plasma. When the de Broglie wavel ength is much less than the distance of closest approach of thermal electro ns, a classical analysis of the plasma can be made. It is assumed, in the c lassical analysis, with (h) over bar -->0, that the energy of the fluctuati ons (h) over bar omega<<k(B)T. Using the fluctuation-dissipation theorem, t he spectra of fluctuations with (h) over bar not equal0 is appreciably decr eased. The decrease is mainly for the highly damped modes at high frequenci es (similar to0.5-3k(B)T). Reaction rates are enhanced in a plasma due to t he screening of the reacting ions. This is taken into account by the Salpet er factor, which assumes slow motion for the ions. The implication of inclu ding the highly damped modes (with (h) over bar not equal0) in the nuclear reaction rates in a plasma is discussed. Finally, the investigations presen tly done on these effects in particle simulations with the sheet model and the multiparticle quantum simulation code are described. (C) 2001 American Institute of Physics.