Most of the prior art designs utilize {HEAD ~ a metal or ceramic ring} around the outer edge of {TAIL ~ the target} to confine the arc, allowing the arc to travel right up to the ring 
Most of the prior art designs utilize { HEAD ~ a metal or ceramic ring } around the outer edge of { TAIL ~ the target } to confine the arc , allowing the arc to travel right up to the ring
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH