Articles techniques et présentations

The transport of intense ion beams with reduced beam divergence over reasonable drift distances requires a reliable space charge compensation (SCC). Negative ion beams (required in the Neutral Beam Injectors envisioned for the ITER tokamak) are here discussed. Secondary particles are generated by beam-gas collisions within the beam volume and their motion is followed by explicit leapfrog time integration; a fraction of the particle exiting the lateral boundaries is injected again.

Poisson equation is solved and fields are accurately retrieved by Comsol Multiphysics at each time integration step; accurate choice of simulation parameters and speeding up techniques are used. Results show the formation of a SCC channel where the beam passes, after a short transition region at drift begin.