Research of capillary Z pinch extreme-ultraviolet light source

Abstract

A preliminary study of a tabletop multi-mode z-pinch x-ray souce is presented. The goal of development of this device was to obtain high densities and temperatures in plasmas of high atomic number elements with two different types of loads: vacuum spark and small (micronscale) wires. In the first mode, the device can be used for x-ray spectroscopic research and calibration of x-ray and vacuum ultraviolet (VUV) diagnostics instrumentation. In the second mode, single wire and x-pinch loads were applied. The device was developed on the basis of a W calibration source developed under a previous Sandia contract, and subsequently transferred to UNR. The existing system was substantially modified to lower the inductance and increase reliability. The system uses a railgap switch, a low-inductance vacuum interface, and a low-voltage (<25 kV), low-impedance, vacuum coaxial transmission line. Circuit modeling of the modified system predicted more than 100 kA into a plasma load from its DC-charged 3 microfarad, 25 kV capacitor bank, with a time to peak current of about 700 ns. This system is compact, and uses no transformer oil or deionized water. The total energy stored in the capacitors bank is up to 800 I with a charge voltage of up to 25 kV. The measured time to peak current is near 700 ns, and typical maximum current of 10&110 kA. The x-ray output energy, pulse duration, and x-ray images fram this plasma source were studied with PCD and XRD diodes and a time-gated pinhole camera. The work was supported by SNL and UNRAn extreme-ultraviolet (EUV) radiation source near the wavelength of 13.5 nm which utilizes a xenon-filled capillaty Z-pinch plasma is presented. The xenon plasma exhibits broadband emission characteristics that offer radiation near 1 I nm and 13.5 nm. A fast-several kA current derived from pulse compression circuit consisting of magnetic switch, a high voltage transformer and a static induction (SI) thyristor stack is applied across the capillary to produce the radiation. The EUV radiation and dynamics of pinching plasma in a capillaly are characterized by employing a photodiode measurement and a high-speed camera in the visible region. A gazing incidence spectrograph is also used to investigate spectral emission from the plasma and the scaling of this EUV light source for lithography.