Spectroscopic study on the temperature evolution of exploding wires in underwater discharges

Summary form only given. As one of the key parameters governing the thermodynamic behavior of the exploding wire, temperature of plasma channel provides useful information to reveal their equations of state and electrical transport properties. Although most spectroscopic approaches
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on deducing the electron temperature in the wire explosions are based on the assumption of blackbody (BB) radiation, the validity of this assumption has not been clearly defined. In this study, continuum radiations emitted from the exploding wires are constructed by means of segmented spectral intensities measured in the visible range with fast photodiode array detector. Results of spectroscopic deduction on the temperature evolution of dense aluminum and copper plasmas during the wire explosions are presented based on the BB assumption. A pulsed power system with a capacitance of 5μF, charging voltage of ~15kV, and peak current of ~ 20kA was used to explode wires of various dimensions. Both the formation of plasma channel followed by current restriking and the combustion of aluminum micro-particles may significantly influence the spectral deviation from the BB
^[1]
. Discharge emissions far deviated from BB are collected to figure out their common features and deviating mechanisms. For the validity of the BB assumption, some criteria are addressed in terms of the thermodynamic state of discharging channel with different initial conditions as well as the circumstances around the wire. Also, the approaches taken by other spectroscopic studies
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are reviewed in this context.