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