Sensitivity Analysis of the Off-Normal Conditions of the SPIDER Accelerator

In the context of the development of the 1 MV neutral beam injector for the ITER tokamak [1], the study on beam formation and acceleration has considerable importance. This effort includes the ion source and accelerator SPIDER (Source for Production of Ions of Deuterium Extracted from an Rf plasma) ion source, planned to be built in Padova, and designed to extract and accelerate a 355 A/m2 current of H- (or 285 A/m2 D-) up to 100 kV [2][3]. Exhaustive simulations were already carried out during the accelerator optimization leading to the present design [4]. However, as it is expected that the accelerator shall operate also in case of pre-programmed or undesired off-normal conditions, the investigation of a large set of off-normal scenarios is necessary. These analyses will also be useful for the evaluation of the real performances of the machine, and should help in interpreting experimental results, or in identifying dangerous operating conditions. The present contribution offers an overview of the results obtained during the investigation of these off-normal conditions, by means of different modeling tools and codes. The results, showed a good flexibility of the device in different operating conditions. Where the consequences of the abnormalities appeared to be problematic further analysis were addressed.