Plasma jets generated by a 1-kJ pulsed-power system

Po-Yu Chang^1*, Cheng-Han Duh¹, Ming-Cheng Jheng^1,2, Chih-Jui Hsieh¹, Mei-Feng Huang¹, Ming-Hsiang Kuo¹, Po-Wei Lai^3,4, Yen-Cheng Lin¹, Jia-Kai Liu¹, Sheng-Hua Yang¹, I-Lin Yeh^1,5

¹Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan city, Taiwan
²National Synchrotron Radiation Research Center, Hsinchu, Taiwan
³Department of Physics, National Cheng Kung University, Tainan city, Taiwan
⁴Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan
⁵Department of Physics, University of California Sand Diego, La Jolla, CA, USA

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

We were studying plasma jets generated by conical-wire arrays which were driven by a 1-kJ pulsed-power system. Solar winds or plasma jets in astrophysical environments were simulated in experiments based on hydrodynamic similarity. Experiments were conducted on the pulsed-power system which provided a pulse current with a peak current of 110±20 kA and a rise time of 1.52±0.06 μs, i.e., a peak power of ~700 MW. On the other hand, the conical-wire arrays consisted of 4 tungsten wires with 20 μm in diameter and 11.55 mm in length. The inclination angle of the arrays was 30⁰. When currents flowed through wires, they were heated and ionized by the current due to Ohmic heating. The plasma ablated away from wires was pushed toward the center of the conical-wire array by the jxB force and eventually merged at the axis of the array. It is called the z-pinch effect. Since the radius at the bottom of the array was smaller than that at the top of the array, the compression happened faster at the bottom than at the top so that a plasma jet moving upward was generated. Several imaging systems were built to image the plasma jets. They were one x-ray pinhole camera with an exposure time as short as 500 ns and two temporal-integrated cameras in the visible-light region. They were used to take the side views and the top views of the self emissions from the plasma jets. Interferometry using a q-switch laser with the single longitudinal mode is underdeveloped for measuring the plasma density. Images of the plasma jets will be presented. This work was supported by the Ministry of Science and Technology (MOST), Taiwan, under Award Number 109-2112-M-006-011.

Keywords: Pulsed-power system, Plasma jet, Conical-wire array, z pinch, X-ray pinhole camera