Electronic processes and electric breakdown of liquid helium

Electronic conduction processes in liquid helium are discussed with respect to their relevance for the initiation of electric breakdown. A recent evaluation of drift data yielded the result that delocalized electrons can exist in liquid He. A lifetime of 5 ns at E = 72 kV/cm was estimated. With respect to the initiation of electric breakdown, it is concluded that under ideal conditions breakdown always starts from the cathode and proceeds in the gas phase. No Townsend type mechanism can occur in the liquid phase.