ENERGY MEASUREMENT OF FAST IONS TRAPPED IN THE TOROIDAL MAGNETIC-FIELD RIPPLE OF TORE-SUPRA DURING ICRF HEATING

Direct losses of ions trapped in the toroidal field ripple of Tore Sup ra were studied, using two techniques. The first (DRIPPLE I) correlate s the ion loss current measured by an electric probe with the ion loss power measured by a calorimeter. As the calorimeter integrates over a ll particle energies and time, it yields only the averaged lost ion en ergy. The second technique (DRIPPLE II), still under development, uses a Faraday cup positioned and filtered so as to select ions by their L armor radius. Preliminary results are useful but the currents measured are small (1-100 nA), and improvements in instrumentation are needed to take full advantage of the data. During ICRH (hydrogen minority reg ime, resonance on-axis), a direct correlation between the lost ion mea n energy and the density of hydrogen (n(H)) is observed. The energy in creases when the hydrogen minority density decreases. Moreover, the li ne integrated density and the lower hybrid (LH) heating also affect th e fast ion losses.