Low-Voltage Capillary Z-Pinches With Short Rise Times and High Currents for Portable Soft X-Ray Ar8+ Lasers

We have experimentally demonstrated low-voltage (35–45 kV) capillary Z-pinches with a short rise time (1012 A/s) and high current amplitude (up to 16 kA) suited for pumping portable soft X-ray (46.9 nm) Ar8+ lasers. We employed a thyratron-driven LC inversion circuit completed by magnetic switch compressor (MSC) technology. The inversion time is synchronized to the switching of the MSC by the proper choice of circuit inductance and the cross section of the core of the MSC surrounded by a “spatially distributed coil” of one winding for the given value (80 nF) of the main capacitor bank, determined by the electric energy to be transferred. The peaking capacitance (44 nF) is distributed around the axis of the spark gap (SG) and the cylindrical capillary-discharge chamber. At a power supply voltage of 25 kV, this charging circuit produced a 45-kV electric pulse with a rise time of 120 ns on the peaking capacitor. The measured capillary Z-pinch characteristics agree well with our model of the electric excitation system. The low voltage (35–45 kV) not only allows for a further decrease in the size of the Ar8+ laser’s excitation part but also a significant shift to the experimental methods, techniques, and technologies widely employed in ordinary discharge-pumped gas lasers operating in the long-wavelength regions of the spectra. Using the low-voltage (45 kV) Z-pinches in an Ar-filled alumina capillary with an inner diameter of 3.1 mm and a length of 22 cm, 46.9-nm laser pulses with an energy of $3 ~\mu \text{J}$ and a beam divergence of 1.9 mrad were generated.