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