Studies of the criteria of exploding a rod

Che-Yu Liu^1*, Shu-Wei Kao², Jui-Che Wang³, Fu-Yu Tsai³, Po-Yu Chang¹

¹Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan, Taiwan
²Department of Photonics, National Cheng Kung University, Tainan, Taiwan
³Sino applied technology Taiwan Co., Taoyuan, Taiwan

* Presenter:Che-Yu Liu, email:xx4185@gmail.com

We studied the dynamics of an exploding rod and found the criteria for exploding the rod. Silicon nanoparticles can be generated during the explosion of a silicon rod so that exploding silicon rods can be widely used in industry. To explode a rod, high current is used to flow through the rod. The rod surface is heated efficiently becoming plasma. Since current always flows in the path with a lower resistance, how the current is distributed between the rod and the surrounding plasma depends on their resistivities. If the resistivity of the surrounding plasma is lower than that of the rod, most current flows through the plasma, and the rod will not explode. On the contrary, the rod can be fully exploded if the rod has a lower resistivity than that of the surrounding plasma. We demonstrated the model by controlling the resistivity by using different materials and different cooling mechanisms. Three different experiments were conducted: (1) A 1 mm × 1 mm silicon rod exploded in vacuum; (2) A 1 mm × 1 mm silicon rod exploded in water; (3) A 1-mm tin rod exploded in vacuum. In each experiment, the rod was driven by a 1-kJ pulsed-power system. The voltage of the pulsed-power system was 20 kV, sufficient to cause a breakdown through the silicon rod. The peak current and the rise time of the pulsed current were ~ 100 kA and ~ 1.6 µs, respectively. Time-resolved shadowgraph, schlieren, and interference images were taken using a 532-nm Q-switch laser with a pulse width of ~ 5 ns. They were used to measure the plasma density and thus infer the plasma temperature. We are showing that only rods in case (2) and (3) were fully exploded which proved that the rod could only be exploded when the resistivity of the rod was lower than that the surrounding plasma.

Keywords: exploding wire, nanoparticles, pulsed-power system