A method 1 and comprising the step of having {TAIL ~ a core collector electrode} having {HEAD ~ a third voltage level} below that of said second voltage level 
A method 1 and comprising the step of having { TAIL ~ a core collector electrode } having { HEAD ~ a third voltage level } below that of said second voltage level
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH