Studies of high-energy-density plasma (HEDP) on a 1-kJ pulsed-power system

Po-Yu Chang^1*, Ming-Cheng Jheng^1,4, Chih-Jui Hsieh¹, Mei-Feng Huang¹, Po-Wei Lai², Yen-Cheng Lin¹, Jia-Kai Liu¹, I-Lin Yeh^1,3, Sheng-Hua Yang¹

¹Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan city, Taiwan
²Department of Physics, National Cheng Kung University, Tainan city, Taiwan
³Department of Physics, University of California San Diego, La Jolla/California, USA
⁴National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Po-Yu Chang, email:pchang@mail.ncku.edu.tw

A 1 kJ pulsed-power system has been built for studying varies topics related to high-energy-density plasma, a regime with pressure greater than 1 MBar in general. The pulsed-power system consists of twenty 1 μF capacitors, two rail-gap switches, two parallel plate transmission lines, and a cylindrical vacuum chamber orientated vertically. Two capacitors are first connected in series forming a brick. Five bricks are connected in parallel forming a wing. Finally, two wings are connected in parallel forming the whole capacitor bank, i.e., 5 μF in total. The system is charged to 20 kV. When it is discharged, a peak current of 110 ± 20 kA with a rise time of 1.51 ± 0.06 μs, i.e., a power of ~700 MW, is provided. It is the pulsed current that will be used to drive different loads for different experiments. In particular but not limited, supersonic plasma jets are generated via imploding conical-wire arrays made of tungsten wires using the pulsed-power system. The phenomena of Martian bow shocks will be studied in the laboratory when the generated supersonic plasma jet flows around an obstacle based on the hydrodynamic similarity between two systems. Another topic we just initiated is to generate extreme ultraviolet (EUV) light for lithography potentially. In this work, an argon plasma plume generated by a plasma gun will be compressed by a theta pinch driven by the pulsed-power system. High temperature can be achieved at peak compression so that EUV light is radiated. To diagnose different experiments, a suite of ultrafast x-ray imaging systems such as time-integrated pinhole camera within 1 μs, a streak camera with a temporal resolution of 100s ps or higher, and a framing camera with a temporal resolution of ns are being built. Interferometry using a q-switch laser with the single longitudinal mode is planned to be used for plasma density measurements. The pulse will be compressed using stimulated brillouin scattering (SBS) in water so that a temporal resolution of 100s ps can be achieved. The characteristics of the pulsed-power system, varies diagnostics, and the conceptual designs of experiments will be shown. This work was supported by the Ministry of Science and Technology (MOST), Taiwan, under Award Number 105-2112-M-006-014-MY3.

Keywords: Pulsed-power system, High-energy-density plasma, plasma jet, EUV light, pinches