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