MeV ion losses measurements in JET using activation technique

Charged particles losses were observed for the first time on JET using an activation technique. Remarkably, these losses were measured in the ceiling of JET tokamak in D-³He plasmas (Bt 3.35T, Ip 2.1MA and in standard field configuration). This technique combined with ultra low-level measurements pushes detection levels significantly lower. Two radionuclides were identified as produced dominantly from charged particles reactions. Quantitative data on charged particle losses were obtained for the first time. Angular distribution with respect to the magnetic field and distribution versus the distance to plasma edge were measured as well. Modelling work of charged particles losses has begun. Some modelling issues need to be addressed. It is unclear yet whether classical drift losses will be sufficient to account for the measured losses. Finally, the technique has wide potential in view of applications to ITER and further development and optimisation is expected on JET.