Modeling xray laser gain in recombining plasmas
Abstract
Optimal conditions for lasing in Hlike and Lilike aluminum as well as in Helike silicon are examined in the context of recombining plasmas. Simulations are carried out for the free expansion of initially hot, dense, and thin cylinders of aluminum and silicon plasmas. Conditions generated from these simulations are input into a simple gain model, yielding information on the state of the plasma variables which maximizes the gain coefficient of a particular lasing transition. The scaling of the maximum gain coefficient with the initial plasma diameter and with the ratio of lasant ions to coolant ions is done for the 3d2p singlet to singlet transition in heliumlike silicon. The theoretical theory and numerical aspects of the principal components of plasma modeling, namely ionization dynamics (ID), magnetohydrodynamics (MHD), and radiative transfer (RT) are presented. The MHD algorithm uses a two temperature Lagrangian gridding method. The ID algorithm utilizes the CollisionalRadiative (CR) model and can integrate all level populations with a stiff differential equation solver or solve by matrix inversion when CR equilibrium is valid. The atomic processes include dielectronic recombination, photoexcitation, photoionization, collisional excitation and deexcitation, threebody and radiative recombination, collisional ionization, and radiative decay. An escape probability formalism is used for the transfer of boundbound, boundfree, and freefree radiation in the RT model.
 Publication:

Ph.D. Thesis
 Pub Date:
 1990
 Bibcode:
 1990PhDT.........9R
 Keywords:

 Laser Outputs;
 Mathematical Models;
 Metallic Plasmas;
 Plasma Physics;
 Power Gain;
 Radiative Transfer;
 Recombination Reactions;
 X Ray Lasers;
 Algorithms;
 Aluminum;
 Ionization;
 Ions;
 Magnetohydrodynamics;
 Photoionization;
 Plasma Dynamics;
 Probability Theory;
 Silicon;
 Plasma Physics