{TAIL ~ The magnetic field} within the duct is adjustable so that {HEAD ~ the emission} of the plasma may be maximized 
{ TAIL ~ The magnetic field } within the duct is adjustable so that { HEAD ~ the emission } of the plasma may be maximized
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH