Fusion Neutron-Induced Soft Errors During Long Pulse D-D Plasma Discharges in the WEST Tokamak

We have performed real-time soft error rate (RT-SER) measurements on bulk 65-nm static random access memories (SRAMs) during deuterium-deuterium (D-D) plasma operation at W-tungsten-Environment in Steady-state Tokamak (WEST). The present measurement campaign was characterized by the production of several tens of long pulse discharges (similar to 60 s) and by a total neutron fluence (at the level of the circuits under test) up to similar to 10(9) n center dot cm(-2), improving the error statistics by a factor of more than 6 with respect to the first measurements obtained in 2020. The experimental results demonstrate the occurrence of bursts of single-event upsets (SEUs) during the most efficient shots and 12% of multiple cell upset (MCU) events. Time-resolved data also show that MCUs are preferentially detected in the last part of these long pulses, providing further evidence that higher energy neutrons, initiated by deuterium-tritium (D-T) reactions due to triton burn-up in the D-D plasma, may play a role in the production of MCUs that cannot be attributed in such large proportions to "low-energy" neutrons produced in D-D reactions.