means for delivering the energy from {HEAD ~ the source} to the inner surface of {TAIL ~ the tubular portion} 
means for delivering the energy from { HEAD ~ the source } to the inner surface of { TAIL ~ the tubular portion }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL