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