AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThA

Paper PS2-ThA9
Particle-in-Cell Simulation of Beam Extraction Through Grid Holes with Application to Neutral Beam Sources

Thursday, November 16, 2006, 4:40 pm, Room 2011

Session: Plasma Modeling
Presenter: S.K. Nam, University of Houston
Authors: S.K. Nam, University of Houston
D.J. Economou, University of Houston
V.M. Donnelly, University of Houston
Correspondent: Click to Email
A particle-in-cell (PIC) simulation of beam extraction through a grid hole in contact with plasma was developed. Particular emphasis was placed on plasma molding over the hole, ion neutralization (by wall collision) in high aspect ratio holes, and the energy and angular distributions of the residual ions and fast neutrals in the beam downstream of the hole. The target application was the generation of neutral beams for future charge-free microelectronics manufacturing. Neutral beam processing requires collimated beams with controlled energy. The ion energy-angular distributions (IEAD), for ions striking the sidewall of the hole, indicated that ions with lower energy tend to be affected more by plasma molding, resulting in larger incident angles on the sidewall. The energy and angular distributions of ions and fast neutrals at different locations along the hole surface showed that ions which neutralize on the top section of the surface of the hole are bad, in the sense that these ions yield divergent neutral beams of relatively low energy. Ions that neutralize along the bottom section of the surface of the hole are good ions, in the sense that these ions yield neutral beams that are less divergent and retain more of the energy of the parent ions. This finding prompted the development of strategies to maximize the fraction of good ions.