The driving mechanism rotates the tubular member and {HEAD ~ electrode} about {TAIL ~ the elongated axis} of the tubular member 
The driving mechanism rotates the tubular member and { HEAD ~ electrode } about { TAIL ~ the elongated axis } of the tubular member
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH