Optimized baffle and aperture placement in neutral beamlines

Most neutral beamlines contain an iron-core ion-bending magnet that requires shielding between the end of the neutralizer and this magnet. This shielding allows the gas pressure to drop prior to the beam entering the magnet and therefore reduces beam losses in this drift region. The beam losses are reduced even further by eliminating the iron-core magnet and the magnetic shielding altogether. The required bending field is supplied by current coils without the iron poles. In addition, placement of the baffles and apertures affects the cold gas entering the plasma region and the losses in the neutral beam due to re-ionization. The placement of the baffles which, determine the amount of pumping in each chamber, and the apertures, which determine the beam loss were varied. A baffler/aperture configuration is for either minimum cold gas into the plasma region or minimum beam losses, but not both.