Integrodifferential models of electron transport for negative ion sources

> Thanks to the presence of a transverse magnetic flux density ( x$]]> and y$]]> where is the extraction axis), the undesired extraction of electrons from a negative ion source is reduced and it is due to collisions. The electron transport is studied with a kinetic model, including Vlasov-Poisson effects and atomic collisions. The integrodifferential equations (IDE) resulting from a reduction to a one-dimensional problem (1-D) by integration on characteristic orbits are strongly affected by the trapped orbits, as here evaluated; a kernel calculation with a partial wave approximation is introduced. Dependencies from the local drift velocity d$]]> and effective Larmor radius e$]]> are found. Solutions are investigated in simple cases with a constant electron current (no additional electron production). Equilibrium solution and electron conductivity are analytically obtained. Presheath solutions are discussed; the approximated conversion to differential equations that are adequate for presheath only (with moderated electric field gradient z,z>-eB_x²/m$]]> ) and their numeric solutions coupled to Poisson equation are reported, and compared to iterative IDE solutions. Examples with different values of e$]]> and mean free path (mfp) ratio are described.