Amplification of stimulated soft x-ray emission in a confined plasma column

An enhancement of \ensuremath{\sim}100 of stimulated emission over spontaneous emission of the C vi 182-A\r{} line (one-pass gain \ensuremath{\sim}6.5) was measured in a recombining, magnetically confined plasma column by two independent techniques involving intensity calibrated extreme xuv monochromators. Additional confirmation that the enhancement was due to stimulated emission has been obtained with a soft x-ray mirror; with 12% measured effective reflectivity of the mirror, a 120% increase in intensity of the C vi 182-A\r{} line in the axial direction was observed.