A similarity model describing the physics of slab target X-ray lasers is constituted from the ideal hydrodynamic equations. The parameters of the plasma(e.g., temperature, density, and scale length) are predicted, which are important for the experimental design of slab target X-ray lasers. The model provides a mathematic tool for quantitatively predicting and explaining experimental results.

By virtue of a simplified model of gain region, the propagation and amplification of soft-x-ray within the plasma with linear electron density profile are studied in the geometrical optics approximation. A simple formulation evaluating the deflection and divergence angles and the maximum x-ray intensity are obtained. The results are in better agreement with experimetally measured data and numerically simulated results.

The best coupling structure of the reflective-type-semicircular-optical fiber probe has been studied by using the method of numerical simulation. Distributive curve of the intensity of the reflective light on the incident plane of the light is given by computer simulation to the different radii of optical fiber cores which are separately 3μm, 5μm, 10μm, 15μm. and the radius of the optical fibers are totally 20m. The results show that the best coupling radius of the reflective type semicircular optical fiber probe satisfies the formula. ρ_max=R-0.01004a³+0.37429a²-3.38095a+16.85714(μm).