Particle transport via gas puff modulation experiments in JET

Plasma fuelling is mandatory for maintaining fusion reactions in fusion power plants. The high temperature and high density SOL of burning plasmas are expected to significantly reduce the efficiency of gas puff fuelling. It is important to investigate how todays high performance H-mode plasmas are fuelled through the pedestal to understand whether ITER and DEMO can rely on gas injection as the main fuelling scheme. ! !The recently upgraded reflectometer diagnostics in JET together with modulated gas puff injection technique are utilised to extract the D and V profiles from a 3-point collisionality scan in L-mode. Furthermore, proof-of-principle tests in H-mode are made with several gas injection locations and frequencies to identify whether modulated density signals are detected and which settings are optimal to use in future parameter scans.!