X-ray laser development experiments at PPPL

An enhancement of ≅ 100 of stimulated emission over spontaneous emission of the CVI 182 A line (one-pass gain ≅ 6.5) was measured in a recombining, magnetically-confined plasma column by two independent techniques using intensity calibrated XUV monochromators. Additional confirmation that the enhancement was due to stimulated emission has been obtained with a soft X-ray mirror. With a 12% measured effective reflectivity of the mirror, a 120% increase in intensity of the CVI 182 A line in the axial direction was observed. Plasma conditions were modeled by computer calculations. Experiments were also conducted using thick carbon fiber targets. For a 4.7mm long fiber, coated with a thin layer of aluminum (for faster radiation cooling), an enhancement of ≅ 6 (gain/length ≅ 6 cm/sup -1/) was measured for the CVI 182 A line without the magnetic field present. The possibilities of developing a laser at wavelengths significantly below 100 A are under intensive study