IMPROVED SENSITIVITY AND SELECTIVITY IN COLLECTOR PROBE EXPERIMENTS BY ANALYSIS WITH RESONANCE IONIZATION SPECTROSCOPY

IN THE FUSION ENERGY PROGRAM, COLLECTOR PROBES ARE AN IMPORTANT TOOL FOR CHARACTERIZING AND UNDERSTANDING THE PARTICLE FLUXES AND ENERGIES IN THE PLASMA EDGE. THE ENERGYOF THE IONS AND NEUTRAL ATOMS IMPINGING ON THESE PROBES IS QUITE LOW, THEREBY LEAVING MOST OF THE PARTICLES CLOSE TO THE PROBE SURFACE. DEPTH PROFILING OF THE COLLECTED MATERIAL GIVES INFORMATION ABOUT THE PARTICLE ENERGY, AND DENSITY MEASUREMENTS GIVE INFORMATION ABOUT THE FLUX AT THE PROBE SITE. PROBE SAMPLES ARE ANALYZED WITH MULTIPLE TECHNQIUES INCLUDING RBS (RUTHERFORD BACKSCATTERING), NRA (NUCLEAR RESONANCE ANALYSIS), AND SIMS (SECONDARY ION MASS SPECTROMETRY). THESE TECHNIQUES ARE OFTEN COMPLEMENTARY, WITH DATA REQUIRED FROM ALL THREE TO GET RELIABLE INFORMATION. SIMS DATA GIVE GOOD DEPTH PROFILES, BUT ARE NOT QUANTITATIVE. TIME-RESOLVED MEASUREMENTS ARE BECOMING MORE IMPORTANT, BUT MAY BE LIMITED FOR MINOR (BUT IMPORTANT)IMPURITIES IN THE PLASMA BECAUSE OF THE SHORT EXPOSURE TIME. SPUTTER INITIATED RESONANCE IONIZATION SPECTROSCOPY (SIRIS) HAS THE POTENTIAL FOR BEING QUANTITATIVE, HAVING GOOD DEPTH PROFILING CAPABILITY, AND ALSO BEING FAR SENSITIVE FOR ALL ELEMENTS THAN PRESENT TECHNIQUES. DURING PHASE I, WE WILL ADAPT THE SIRIS TECHNIQUE TO THE SPECIAL REQUIREMENTS OF PLASMA DIAGNOSTICS. DEVELOPMENT OF INSTRUMENTATION ENABLING RAPID ANALYSIS OF PROBE SAMPLES AT PLASMA FACILITY SITES IS PLANNED DURING PHASE II.