The influence of insulating coatings on the energy deposition and plasma morphology of the electrical explosion of aluminum and tungsten wire

摘要

Summary form only given. The electrical explosion of metal wire plays significant role in many applications, such as synthesis of nanopowder, dense plasma generation and wire-array Z pinch1, etc. In the initial stage of the wire-array Z pinch, every single wire are exploded into core-corona structure, i.e., the high-density, low-temperature core surrounded by the high-temperature, low-density corona plasma. The plasma column has great influence on the stagnation stage of the wire-array Z pinch. The homogeneity of the plasma column is determined by the energy deposition in the metal wire. Therefore, the investigation on the energy deposition and morphology of the electrical explosion of metal wire is very important for the understanding of the physics of the wire-array Z pinch. In this paper, a set of experimental results of electrical explosion of aluminum and tungsten wires with and without insulating coatings are presented. The process of energy deposition derived from the exploding wires with and without insulating coatings are compared and analyzed. Enhanced energy deposition is achieved in exploding aluminum and tungsten wires with insulating coatings. A laser probe (EKSPLA-PL2251C, 532nm, 30ps) is applied to construct the shadowgraphy, interferometry and schlieren diagnostics to give detailed information about the morphology of the exploding products. The shadowgram and schlieren images present the morphology of the high-density core and the front of the high density gradient of the neutral atoms and plasma, respectively. The interference phase shift is reconstructed from the interferogram. The shadowgram of the exploding aluminum wire with insulating coatings demonstrate a structure of strata. Although the energy deposition in the coated tungsten wire is enhanced substantially, the shadowgram of the exploding tungsten wire with insulating coatings show a severe inhomogeneous structure of energy deposition. The barrier of the energy deposition in the exploding coated tungsten wire is analyzed.