Estimating and projecting operating fields for liquid dielectrics in KrF laser fusion power plants

Krypton fluoride (KrF) laser fusion power plant designs include pulsed oil and water dielectrics with very large electrode areas that must operate continuously and reliably for years at 5-10 pulses per second. Operating electric fields must be maximized to minimize size and cost. To obtain a better understanding of design criteria for the electric fields the authors discuss the statistical treatment of breakdown probability. They also examine the use of the published area effects for breakdown of oil and water; the authors suggest that at very large areas the results may have been controlled by the presence of large impurities and that engineering criteria for limiting the type and size of these can allow reliable operation at fields higher than those predicted by the accepted area effects in oil and water. Other factors that might raise or lower safe operating fields are discussed, as are polarity effects. A system is described that will be used for accelerated tests of oil and water insulation to reduce the uncertainties in the choice of operating fields for fusion power plants.