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