Stripping of ion beams by multiple passes through a plasma medium

A method to increase the charge state of multicharged ions is explored. The method is based on stripping, during multiple passes, of an initially low charge-state ion beam through a plasma medium with energetic electrons heated at the electron cyclotron resonance. The key feature of the system is a magnetic recirculating line which has a built-in stripping chamber and a system of entrance-exit apertures. The recirculating line comprises a magnetic low-loss ion guide which delivers ions being passed through the stripping chamber to its entrance. As a stripping medium, a hydrogen plasma confined in a magnetic trap of cusp configuration is proposed. To model the conversion of initially injected ions with charge state [formula omitted] to higher states, basic parameters of the stripping chamber can be estimated as follows: microwave frequency: 14.4 GHz; effective plasma length 10–30 cm; gas pressure: [formula omitted] Torr. Results of numerical calculation of the proposed stripping process show that an increase of ion charge is possible with acceptable deterioration of ion beam characteristics. Conversion efficiency, for example, for [formula omitted]Pd from [formula omitted] to [formula omitted] for these parameters is about 80%. © 1998, American Institute of Physics. All rights reserved.