Excitation-velocity and group-velocity mismatch in amplified spontaneous emission lasers: A discussion on the transient gain x-ray lasers - art. no. 034701

A discussion on the roll-off in the emitted intensity in transient collisio nal excitation (TCE) schemes for x-ray lasers is presented. The high gain i n TCE lasers results in a group velocity significantly below the light velo city for the amplified pulse. This effect is proven to be the main reason t hat the measured gain coefficients fall considerably short of theoretical p redictions. Is is outlined how a more effective excitation can be achieved when using the TCE scheme.