Impact of discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser

The very important role played by the discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser has been experimentally established. The discharge current profile was varied either by making the current faster and keeping its peak value fixed or by increasing its peak value and keeping the duration fixed. When the dI/dt value was increased from 7.5 × 1011 to 9.2 × 1011 A s−1 by making the current faster, the soft x-ray laser efficiency was found to be enhanced significantly. This was reflected by a substantial increase (~48%) in the gain-coefficient of the x-ray laser from 0.69 cm−1 to 1.02 cm−1 respectively. The effect of current amplitude on the gain-coefficient was also studied by measuring the gain-coefficient for different current amplitudes while keeping the duration fixed. It was found that there exists an optimum value of discharge current amplitude at which the gain-coefficient becomes maximum. Using such optimization, the gain-coefficient could be further enhanced to 1.33 cm−1 which is ~93% higher than the earlier value of 0.69 cm−1.