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P: Plasmaphysik
P 1: Magnetic Confinement and Plasma Wall Interaction
P 1.3: Vortrag
Montag, 2. April 2001, 17:00–17:15, 2053
Compound pellets for improved tokamak plasma refueling — •M. Reich1, P.T. Lang2, R. Dux2, A. Lorenz2, V. Mertens2, H.W. Müller2, J. Neuhauser2, K.F. Renk1, ASDEX Upgrade Team2, and 3 — 1Institut für Experimentelle und Angewandte Physik, NWF II, Universität Regensburg, D-93040 Regensburg — 2Max Planck Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching — 3
Injecting cryogenic hydrogen isotope pellets from the magnetic high field side into a tokamak is an advanced refueling method capable of improving the accessible operational area. Deep particle deposition is required to minimize particle and energy flux out of the plasma after the pellet injection. One option to achieve deeper penetration and deposition is to improve the pellet injection speed, as recently demonstrated in experiments performed at ASDEX Upgrade. The headroom for further speed improvement is limited due to technological restrictions for the inboard launch and the pellet fragility. A novel approach to enhance pellet penetration is the use of compound pellets produced from doped hydrogen. First, doping is expected to improve the mechanical stability and thus to allow for another increase in pellet speed. Second, additional radiative cooling by impurities is expected to reduce the heat flux onto the pellet surface resulting in deeper penetration. First test results are presented indicating mechanical properties of doped pellets and giving estimates of concentration levels for different medium-Z dopands sustainable in a low-Z plasma.