STRONGLY ENHANCED SOFT-X-RAY EMISSION AT 8 NM FROM PLASMA ON A NEODYMIUM-DOPED GLASS-SURFACE HEATED BY FEMTOSECOND LASER-PULSES

We have demonstrated efficient soft x-ray generation from femtosecond laser plasma created on a neodymium-doped glass target. Nd ions doped in glass target enhanced soft x-ray emission near 8 nm without broaden ing the soft x-ray pulse duration when there is no prepulse. A weak pr epulse caused strong enhancement in soft x-ray intensity at 8 nm. By i ntroducing a prepulse at 50 ns before the main pulse, 1% energy conver sion efficiency from laser pulse into soft x-ray at 8 +/- 0.5 nm was a chieved by using a neodymium-doped glass target. This value is 1.2 tim es as high as that for Nd metal target case. (C) 1998 American Institu te of Physics.