magnetic poles placed at exit part of ion source and a magnetic pole in a center of a discharge channel in a form of protrusion with {HEAD ~ a magnet} or electromagnet placed in {TAIL ~ a central magnetic pole} 
placed in
magnetic poles placed at exit part of ion source and a magnetic pole in a center of a discharge channel in a form of protrusion with { HEAD ~ a magnet } or electromagnet placed in { TAIL ~ a central magnetic pole }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL