Energy recovery of residual ions may be needed to increase the energy efficiency of Neutral Beam (NB) injectors for fusion plants as DEMO while a deflection-based system has been proposed up to now to dump residual ions. As an alternative, a compact beam energy recovery system, based on space charge effects due to the residual ion deceleration into 2 Farady Cups (FC) with holes for D0 passage, can replace the Electrostatic Residual Ion Dump (ERID) designed for ITER and DDT projects to dump the residual D- and D+ before the NB injection in the tokamak plasma. All parameter tunings and simulation are here described, also providing the suppression of backstreaming to the ion source. Ion energy spread Ed and rectangular geometry are considered. Collection of ions at low energy (a few percent of the full neutral beam energy Ki) instead of Ki as in ERID gives advantages that will be discussed.
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|Project INFN-E, and INFN-CSN5 (experiment Plasma4beam and Ion2Neutral)