First MeV ion loss measurements using activation technique in reversed B experiments at JET

Fast ions measurements become increasingly important as we move closer to the International Thermonuclear Experimental Reactor (ITER) or burning plasma experiments and further R&D is especially required in the field of fast ion loss measurements [Bonheure et al., Rev. Sci. Instrum. 74, 1726 (2003).] in the perspective of ITER. A boron target mounted on a manipulator was exposed to deuterium plasmas during reversed field experiments at the Joint European Torus (JET). Due to the ¹⁰B(p,a) ⁷Be reaction, ⁷Be is produced in the boron target by MeV protons escaping the plasma. The proton losses are deduced from measurements of the intensity of decay emission of ⁷Be. Excellent agreement is found between measurements and prediction from fast ion classical drift losses. The MCORBIT Monte Carlo Simulation code was used to predict unconfined orbits fraction. Further developments are presented, including a new dedicated instrument to be used in experiments already planned at JET with ion cyclotron range of frequency accelerated alpha particles. The obtained results will be essential for the design of lost alpha diagnostics on ITER based on activation technique.