The overvoltages with multiple reignitions
correspond to the plots circled in Fig. 4. Only these
plots show lower values than those expected from Eq.
( 1). The overvoltages do not become larger than the
dielectric strength of the vacuum gap since the vacuum
gap is unable to withstand the large overvoltage, and
breakdowns occur. The withstanding voltage of the
vacuum switch regulates the overvoltage by
breakdowns.