Modified He Ion Source Using Cs Vapor Charge Exchange

Earlier versions of the He- source suffered from cesium metal collecting on insulators and entering the r. f. source. A single acceleration gap is used to reduce the number of insulators requiring protection and additional shielding of the remaining insulators is provided. The new version also uses a gridded focusing element. Additional baffling and smaller entrance and exit apertures for the exchange canal have eliminated the flow of cesium vapor into the r. f. source. A further modification to produce higher current adds an einsel lens between the r. f. source and the exchange canal.