Ions are trapped in {HEAD ~ a potential well} in the linear trap 30 and are bunched at {TAIL ~ the bottom} of the potential well adjacent an exit segment 50 
Ions are trapped in { HEAD ~ a potential well } in the linear trap 30 and are bunched at { TAIL ~ the bottom } of the potential well adjacent an exit segment 50
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH