An Ne-like transient collisional excitation x-ray laser at 19.6nmj (J-0→1.3P→3S) was investigated unmerically using a sopohisticated hydrodynamic code for a 100μm thick Ge plannar target irradiated by a nanosecond pre-pulse followed by a picosecond main optical laser pulse. The simulations indicate that for a given peak intensity, the main pulse has an optimal duration to generate the maximum effective gain, An effective gain as high as 200cm-1 was obtained for the optimized drive pulse configuration.