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