Modeling x-ray laser gain in recombining plasmas

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:7271114

Roelant, D F

Optimal conditions for lasing in H-like and Li-like aluminum as well as in He-like 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 3d-2p singlet to singlet transition in helium-like silicon. The modeling of plasmas, whose densities are too low for Local Thermodynamic Equilibrium (LTE) to be valid but whose opacities are too high for application of the optically thin approximation, requires the transportation of radiation for accurate simulations. Presented here are the theory and numerical aspects of the principal components of plasma modeling, namely ionization dynamics (ID), magnetohydrodynamics (MHD), and radiative transfer (RT). The MHD algorithm uses a two temperature Lagrangian gridding method. The ID algorithm utilizes the Collisional-Radiative (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 de-excitation, three-body and radiative recombination, collisional ionization and finally radiative decay.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• OSTI ID: 7271114
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
426002* -- Engineering-- Lasers & Masers-- (1990-)
ALGORITHMS
ALUMINIUM
AMPLIFICATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EQUILIBRIUM
EXCITATION
FLUID MECHANICS
GAIN
HYDRODYNAMICS
IONIZATION
LASERS
LTE
MAGNETOHYDRODYNAMICS
MATHEMATICAL LOGIC
MATHEMATICAL MODELS
MECHANICS
METALS
PHOTOIONIZATION
PLASMA
PLASMA DENSITY
PLASMA SIMULATION
RADIATION TRANSPORT
SEMIMETALS
SILICON
SIMULATION
X-RAY LASERS