{HEAD ~ The electrically conductive barrier} enables {TAIL ~ a very large accelerating voltage} to be used without causing discharge through any gaseous medium in the microscope sample chamber 
{ HEAD ~ The electrically conductive barrier } enables { TAIL ~ a very large accelerating voltage } to be used without causing discharge through any gaseous medium in the microscope sample chamber
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH