Abstract
Using the SIMION program, we have calculated the trajectories of hydrogen ions to investigate the effects of an E × B filter to be used for hydrogen ion beam injection experiments. The geometry we have utilized for the simulation matches the ion beam transport system of the DT-ALPHA device. Before investigating the hydrogen ion trajectories, we calculated helium ion trajectories and compared the results with experiments using a helium ion beam to confirm the results of the SIMION calculations. We then calculated the trajectories of the hydrogen ions H+, H2+, and H3+. We found that the electric field required to select an H+ ion beam differs from that obtained from a theoretical calculation, and we interpret this as a result of the fringe fields of the E × B filter. We have also evaluated the H+ ion beam size at the ion entrance aperture using SIMION. This calculation indicates that spreading of the hydrogen ions along the electric and magnetic fields differs because of non-homogeneous fields and the fringe fields of the filter. In addition, we have investigated the trajectories and beam sizes of He+ ion beams, we found that the E × B filter has no significant influence on the He+ ion beam experiments.
