Neutral particle analyzer/isotope separator for measurement of hydrogen isotope composition of JET plasmas

This article describes a neutral particle analyzer/isotope separator (ISEP) developed for measurement of the relative hydrogen isotope composition of Joint European Torus (JET) plasmas. The ISEP deployed on the JET can be regarded as a prototype of an instrument proposed for measurement of the spatial profile of the ratio of the density of deuterium and tritium ions in the plasma, nD(r)/nT(r), in the International Thermonuclear Experimental Reactor (ITER). The ISEP makes simultaneous measurements of the energy distribution of efflux of hydrogen isotope atoms (H, D, and T) from the plasma. From such measurements it is possible to deduce the radial profile of the relative hydrogen isotope ion composition of the plasma and radial transport of ions of one isotope across the plasma of another isotope species. The main elements of the ISEP are (a) use of a thin carbon foil for reionization of the incident atoms, thereby eliminating gas stripping cells and gas sources of conventional neutral particle analyzers (...