Study On The Mechanism And Characteristics Of Electrically Exploding Wire

Electrically exploding wires have been studied comprehensively and profoundly under the need of pulse power modulating technology since 1970s'. As a result, some effectively theoretical models and empiric formula attained are fit for exploding-wire opening switch which would be run in 10 U s-level pulse. Dynamics and instability of plasma initiated by ns-level electrically exploding wires or electrical intermedia have been studied also during 1980s and 1990s as an artifice for the basic study of fusion plasma. As we know, the scheme and characteristices of plasma column initiated by exploding wires under prepulse condition in wire array Z pinch implosion experiments have much significance for improvement of Z pinch implosion technology. This is just the background of the dissertation . As a x-ray source, Z pinch implosion is so effective that many studies on annular gas puff and wire array have been carried out since 1970s'. With the improvement of driver's technology and capability , some critical purposes have been arrived to . That include the enhancement of wire array mass matched to driver , the melioration of plasma liner , the elevation of stability , the improvement of yields and power for wire array Z pinch implosion as the radiation source. The possibility for Z pinch implosion's applications in many physical experiments has been inaugurated since the yields and power of x-ray output in double wire array experiments have reached 2MJ and 290TW respectively in Sandia National Laboratory in 1997.Early stage during dense wire array implosion include single wire s heating, vaporizing, ionizing and singe wire-initiated plasma columns expansion with prepulse. Main current of Z pinch is loaded and then it driven the plasma liner to implode when singe wire plasma column touches and couples with each other. Single wire plasma column's state and coupling condition are such critical factors to determine the initial uniformity of imploding plasma liner that they influent the development level of R-T instability for plasma liner during implosion stages, the stagnation's symmetry and shrinking rate for plasma liner on implosion axis, the x-ray's yields and power for plasma liner at the time of stagnation.The "r-t" curves representing correlation between exploding wire-initiated plasma column s radius and time are studied on theoretically and experimentally in this papers. Physical model of the exploding wire-initiated plasma's respondence to the electromagnetic and thermal pressure are founded theoretically. Numerical simulations which include the stages of wire's heating, vaporizing, ionizing, and plasma's forming have been done with 1-D MHD program, and "r-t" curves for corona encircling the dense wire core are got. Two elementary pulse power systems are established in our laboratory. The experiments are carried out with these setups. In experiments, the electrical data are recorded by digital oscilloscope and the "r-t" curves are obtained with SJZ-15 high speed scanning photographer. All of the data begin with the moment of trigger pulse's emergence. Theoretical results are corresponded to experimental yields basically. On the basis of the data's analysis, preliminary study on the scheme of electrically exploding wire is done.The study results can be used in wire-array Z-pinch physical experiments directly and that may have promotion effect to the parameters's optimization of wire-load target chamber .