Integration of the Magnetic Field Design for SPIDER and MITICA Negative Ion Beam Sources

The design of the magnetic field configuration in the SPIDER and MITICA negative ion beam sources has evolved considerably during the past four years, with respect its original design [1, 2]. This evolution, passing through intermediate steps [3, 4], was driven essentially by three factors: a) the experimental results of the large RF - driven ion sources at IPP (mainly BATMAN and ELISE), which have provided valid indications on the optimal magnetic configurations for reliable RF plasma source operation and for large negative ion current extraction, b) the comprehensive beam optics and heat load simulations, which showed that the magnetic field configuration in the accelerator was crucial for keeping the heat load due to electrons on the accelerator grids within tolerable limits, without compromising the optics of the negative ion beam in the foreseen operating scenarios, c) the progress of the detailed mechanical design of the accelerator, which stimulated the evaluation of different solutions for the correction of beamlet deflections of various origin and for beamlet aiming. On this basis, various new requirements for the magnetic field configuration in the SPIDER and MITICA beam sources have been progressi vely introduced and updated until the design converged. The paper presents how these requirements have been integrated into the final design solution