Eur. Phys. J. D 14, 349-359 (2001)
https://doi.org/10.1007/s100530170202

Statistics of inter-particle distances and angles in plasmas

Faculty of Physics, Weizmann Institute of Science, Rehovot 76100, Israel

Corresponding author: ^a fndima@plasma-gate.weizmann.ac.il

Received: 27 October 2000
Revised: 30 January 2001
Published online: 15 June 2001

Abstract

Accurate treatment of the plasma density effects requires a detailed knowledge of the spatial distribution of individual ions around a test ion. In the present work, rigorous expressions are derived for the main 2- and 3-particle spatial distribution functions involving the nearest neighbor (NN) and the next-nearest neighbor (NNN) ions. These expressions, valid for both ideal and nonideal plasmas, present the distributions as functionals of the potentials U_NN and U_NNN at the nearest and next-nearest ion locations. All of the distribution functions except one are derived and discussed in the present work for the first time ever. For utilization of our results in practical calculations, we suggest semi-empirical expressions for U_NN and U_NNN in the ion-ion coupling parameter range . In order to test the accuracy of our expressions for U_NN and U_NNN we conduct Molecular Dynamics (MD) simulations. The simulations utilize the pure Coulomb particle-particle interaction potentials, regularized at close range to avoid classical Coulomb collapse, and are free from the assumptions made to find U_NN and U_NNN. Thus, the results of the MD simulations provide an independent test of our theoretical results. Excellent agreement has been found between the results of the theory and of the MD simulations. Finally, we outline the implications of the present findings on the problem of tunneling and charge exchange in dense plasmas.