One of the electrodes includes openings for allowing {TAIL ~ the vapor} to enter {HEAD ~ the space} 
One of the electrodes includes openings for allowing { TAIL ~ the vapor } to enter { HEAD ~ the space }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD