Loss cone structure for ions in the TJ-II helical axis stellarator Part II: Radial electric field effects

Previous studies are extended of losses and trapping for collisionless ions of low and intermediate energy (0.1-1 keV roughly), done for the TJ-II helical axis stellarator, to the case where radial electric fields are present. The modifications produced by the electric field on the radial profile of losses, the angular distributions at the plasma exit and the impact patterns on the TJ-II vacuum vessel are analysed showing a progressive peripheral concentration and a slow rotation of the distributions of lost particles at the plasma exit and on the vacuum vessel in the direction of the poloidal rotation induced by the electric field. Changes in radial and angular trapping distributions are discussed, showing the relative insensitivity to the electric field of the angular positions where the maxima and minima of trapping occur. The effect of the electric field resonances is analysed and there is a discussion of the order of appearance of the different TJ-II magnetic configurations and the influence on trapping and losses. The modifications produced by the electric field and the resonances on the different loss cone diagrams are analysed and explained.