This provides {TAIL ~ reliable operation} of the arc for a wide range of the cathode sizes and {HEAD ~ shapes}, and at low to very high power levels 
This provides { TAIL ~ reliable operation } of the arc for a wide range of the cathode sizes and { HEAD ~ shapes } , and at low to very high power levels
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH