Tritium depth profiling in carbon samples from fusion experiments

Tritium depth profiling measurements by accelerator mass spectrometry have been performed at the facility installed at the Rossendorf 3 MV Tandetron. Hydrogen and deuterium profiles are measured with the Faraday cup between the injection magnet and the accelerator, while the tritium is counted after the accelerator with semiconductor detectors. Depth profiles have been measured for carbon samples which had been exposed to the D,D plasma at the first wall of the Garching fusion experiment ASDEX-Upgrade and from the European fusion experiment JET, Culham/UK, which had been operated part time with a D,T plasma. The tritium contents of the samples from JET were up to six orders higher compared to the samples from ASDEX-Upgrade. The problem of the detector overloading during measurements of samples with a medium tritium content has been solved by installation of a scanning system in the AMS beamline, which enables defined scanning of the tritium beam over an aperture in front of the detector. The tritium beam current from samples with high tritium content has been measured directly in the Faraday cup before the accelerator. A dedicated AMS facility with an air-insulated 100 kV tandem accelerator is under construction.