Kiel 2011 – scientific programme

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P: Fachverband Plasmaphysik

P 19: Poster: Hochtemperaturplasmen: Experiment und Diagnostik

P 19.6: Poster

Wednesday, March 30, 2011, 16:30–18:30, Foyer

A room temperature pellet launcher for ELM trigger investigations in ASDEX Upgrade — Athanassios Alexiou¹, Ralph Dux², Kinga Gál³, Peter Lang², •Rudolf Neu², Bernhard Plöckl², Stefan Sotier¹, and ASDEX Upgrade Team² — ¹University of Applied Sciences, Lothstrasse 34, 80335 München, Germany — ²MPI für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany — ³KFKI Research Institute for Particle and Nuclear Physics, PO Box 49, H-1525 Budapest-114, Hungary

Pacing to mitigate edge localized modes (ELMs) is regarded essential for the protection of the ITER Divertor. However, pacing is currently based on cryogenic Deuterium (D) pellet injection unusable in the first non-nuclear phase of ITER. A new idea to overcome this is the use of Beryllium pellets. To perform according trigger tests at AUG, Aluminum (Al) pellets will be used as they are easy to handle, cheap and resulting radiative losses in according H-mode plasmas seems manageable for sufficiently small pellets. An existing room temperature solid state injector was recovered basing on gas drag acceleration capable to launch one pellet per plasma discharge for an ELM trigger experiment. Pellets with 0.5 mm diameter, containing about 4 × 10¹⁸ Al atoms can be launched in the speed range of 60 - 375 m/s using Helium propellant gas pressures from 5 to 100 bar. Reliability close to 1 was observed for pellets in free flight, while guiding pellets through the narrow existing injection tube would cause a reduction to about 0.3. Hence, a revision of the torus access allowing for free flight injection covering an about 1.5 degree (FWHM) pellet trajectory cone angle are under way.