Investigations on high power neutral beam production for tokamak applications

The development of a two fluid, one dimensional code in cylindrical geometry enables to study and describe the spatio-temporal evolution of negative hydrogen (or deuterium) ions and electrons in a magnetically insulated diode. The code is applied to test experimental data from the international literature on pulsed power devices producing high voltage and high current negative ion beams in order to investigate the physical processes of the acceleration and the extraction of the beam. The numerical results of the code are in good agreement with the experimental data using the appropriate physical and the geometrical parameters of the devices. These investigations allow to propose a new scheme for the production of a high power (~100MW) neutral beam, based on different well established technologies such as: (a) the production of negative ions by ultra-short laser beam interaction with clusters, (b) the coupling of a magnetically insulated diode with a pulsed power device capable to extract high current (200 A) and high energy (1 MeV) negative ion beam and (c) laser based photodetachment techniques for beam neutralization. The proposed scheme has applications to Tokamak reactors.