{HEAD ~ Electrodes} are disposed in the medium and are closely spaced such that the application of a high voltage will cause {TAIL ~ arc discharge} across the same 
{ HEAD ~ Electrodes } are disposed in the medium and are closely spaced such that the application of a high voltage will cause { TAIL ~ arc discharge } across the same
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH