Comparison of neon-like germanium inner shell and nickel-like gadolinium lasing at 62 Å and 66 Å by picosecond heating of a preformed plasma

Abstract

Simulations are presented to compare the output of the 62 Å inner shell transition in germanium with the 66 Å traditional J=0→1 gadolinium transition, using 280 ps pulses with a maximum of 100 J energy and a 30 J, 3 ps pulse, of peak intensity 1.5×10 15 W cm −2, focussed onto a 1 cm long, 100 μm wide slab target. Saturated output appears possible for gadolinium assuming the implementation of a suitable travelling wave pumping scheme. Saturation was achieved in this configuration using two long pulses of peak intensity 8×10 12 W cm −2 and the CPA pulse, leading to an output power of ∼14 MW. Under these pulse restrictions, the germanium inner shell does not achieve saturation. Simulations indicate that saturation may be achieved if the CPA pulse intensity is fractionally increased (to ∼2×10 15 W cm −2). The output power of germanium is ∼1 MW, due to a smaller near field area. Raytracing for both schemes predicts a far field deflected angle of ∼3 mrad. Simulations indicate the potential of these schemes for successful X-ray lasing at wavelengths of ∼65 Å.