The controller 52 uses this approximate average to control {HEAD ~ the magnitude} of power to {TAIL ~ both electrodes} 
The controller 52 uses this approximate average to control { HEAD ~ the magnitude } of power to { TAIL ~ both electrodes }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL