Low-inductance, low-impedance megawatt average power load

A compact, low-inductance, 0.5-Ω, 1-MW average power resistive load has been developed to facilitate testing of the MAPS-40 thyratron. The flowing liquid electrolyte system uses the large thermal mass of a storage tank of electrolyte to store the energy which is dissipated through a heat exchanger after the high-power run. The electrolyte starting temperature, flow rate, and allowable temperature rise determine the maximum average power into the load; the external and internal spacings and flow uniformity determine the maximum peak power; the flow rate and storage volume determine maximum running time. The load assembly consists of two parallel glass pipes 10.2 cm in diameter and 15.25 cm long. The active volume in each pipe is 6.35 cm long and is contained between electrodes 8.9 cm in diameter. The two sections of the load are electrically in parallel and flowing in series, putting both flow connections at ground potential. The major problem was getting the internal flow pattern uniform to eliminate local boiling and arcing across the bubbles while keeping the pressure drop low and flow high. The calculated inductance of the load assembly is 11 nH, and the structure lends itself to coaxial connections which reduce the overall inductance still further. Material compatibility with the electrolyte will be discussed.