AQUEOUS-ELECTROLYTE RESISTORS FOR PULSED-POWER APPLICATIONS

Aqueous-electrolyte resistors were developed for use as dummy loads in pulsed power systems. These resistors are simple, robust, low-inducta nce devices capable of operation at high voltage and high current, and may be used to dissipate large pulse energies without catastrophic fa ilure. The resistivity and temperature coefficient of resistivity were measured for several candidate electrolytes, including aqueous soluti ons of copper sulfate, potassium and aluminum sulfate, potassium dichr omate, silver nitrate, sodium dichromate, and sodium thiosulfate. The resistivity of potassium dichromate solution is expressed by the power law rho(Ohm)=1640 C-(1.0942) for electrolyte concentrations in the ra nge C=0.025-25 g/l. The temperature coefficient of resistivity is in t he range (1/rho)(partial derivative rho/partial derivative T-s)=-(0.01 -0.03)/degrees C for typical aqueous metal-salt electrolytes and is de pendent on the solution temperature T-s and, to a lesser extent, on th e electrolyte concentration. Aqueous solutions of potassium dichromate are compatible with brass, copper, and stainless-steel electrodes and polycarbonate and polymethylmethacrylate insulators, even at high con centration and elevated temperature. Such resistors give long shelf an d operational lifetimes. If the maximum allowable resistance change (d ecrease) during the pulse is 10%, then the energy deposition per unit volume of electrolyte solution is limited to approximately 20 J/cm(3) for resistors initially at room temperature. (C) 1995 American Institu te of Physics.