Some error studies for interface management in the HEBT of the IFMIF accelerator

The IFMIF accelerator system is based on two similar beam lines running in parallel. Each D+ beam of 40 MeV/125 mA is transported by a high energy beam transport (HEBT) line up to the liquid lithium target where neutrons will be produced. On the target, the specifications of the beam footprint mentioned a rectangular shape (20 cm × 5 cm) with a flat-topped homogeneous current density profile and small energy spread. The two beams footprints will overlap, doubling the current density on target and thus increase the neutron flux. As the specified beam conditions on lithium target are so stringent to achieve a stable neutron irradiation field, effects of errors due to misalignment and mis-accelerated condition at the entrance of HEBT are studied using multi particles simulation technique. The tolerance on beam axis off-set at HEBT inlet, without any orbit correction, is estimated around ±0.2 mm. Large energy deviations (larger than 2.5%) show small footprint robustness in case of mis-accelerated situation but better robustness for over-accelerated condition.