Articolo in rivista, 2013, ENG, 10.1088/0963-0252/22/4/045019

Three-dimensional structure of the extraction region of a hybrid negative ion source

Taccogna, F. and Minelli, P. and Longo, S.

IMIP CNR, Bari, Italia Università di Bari "Aldo Moro", Dipartimento Chimica, Bari, Italia INAF Osservatorio Astrofisica Arcetri, Firenze, Italia

A self-consistent three-dimensional particle-based model of the source extraction-acceleration transition region of a surface-produced negative ion source is developed. Some considerations are advanced on the characteristic of negative ion transport: it is purely electrostatic while collision-induced (charge exchange with atoms) and magnetic-induced (ion gyration around the filter field) transport contributions play no relevant role in H-extraction. In fact, the calculations presented here indicate that the key point is the penetration of the extraction grid field inside the plasma grid collar and the source region, which helps in removing the negative ions produced on the surface. This study suggests that the best plasma grid shape is characterized so as to allow the extraction field to arrive directly on the surface-emitting H- ions and that the best aperture size is directly related to the particular shape used.

Plasma sources science & technology (Print) 22 (4)

Keywords

CNR authors

Longo Savino, Taccogna Francesco, Minelli Pierpaolo

CNR institutes