{TAIL ~ The distal ends} of the electrodes are positioned at a central volume of {HEAD ~ the airtight vessel} 
{ TAIL ~ The distal ends } of the electrodes are positioned at a central volume of { HEAD ~ the airtight vessel }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD