Carbon Migration during JET 13C Experiments
JET performed two dedicated migration experiments on the final run day of separate campaigns using 13CH4 methane injected into repeated discharges. The 13C deposition was measured by IBA and SIMS techniques on removed vessel components from one poloidal location. One experiment used localized injection into L-Mode plasmas from the vessel top. In the second, the methane introduction was dispersed toroidally near the outer strike point in Type I ELMy H-Mode plasmas. The EDGE2D/NIMBUS code has been used to model carbon migration in both experiments. The important migration pathways were: (1). Re-deposition and erosion near the injection location, (2). Migration through the main chamber SOL, (3). Migration through the private flux region, and (4). Neutral migration originating near the strike points. In H-Mode, the migration is influenced by the ELM cycle.