{HEAD ~ an ionic current detection means} which applies a voltage across a pair of electrodes installed in a combustion chamber of the internal combustion engine, and detects {TAIL ~ the ionic current} flowing between the pair of electrodes through ions generated when the gas mixture in the combustion chamber has burned 
detects
{ HEAD ~ an ionic current detection means } which applies a voltage across a pair of electrodes installed in a combustion chamber of the internal combustion engine , and detects { TAIL ~ the ionic current } flowing between the pair of electrodes through ions generated when the gas mixture in the combustion chamber has burned
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH