Optimizing the performance of nickel-like collisionally pumped x-ray lasers. III. Exploding foil lasers for the wavelength range below 50 Å

In previous work, it was found that heat conduction limited the development of laser action at wavelengths below 50 Å. In this paper, we discuss the use of thin foils to limit these effects, and generate a high-density and -temperature plasma with low refractive index gradient. By using a relatively short (~100 ps) first pulse and short (~1 ps) second, it is shown that effective high-gain systems may be developed.