Bonn 2000 – scientific programme
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P: Plasmaphysik
P 18: Plasmatechnologie (Poster)
P 18.3: Poster
Wednesday, April 5, 2000, 10:30–13:00, Aula
Pellet acceleration scheme for centrifuge injectors supplied by continuously working extruders — •P.T. Lang1, M.J. Watson2, P. Twynam2, A. Walden2, S. Wijetunge2, B. Willis2, N. Hosogane3, H. Hiratsuka3, and K. Kizu3 — 1Max Planck Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching — 2JET Joint Undertaking, Abingdon, Oxfordshire, United Kingdom — 3JAERI, Naka Fusion Research Establishment, Ibaraki-ken, Japan
To investigate tokamak refueling by injection of cryogenic mm size deuterium pellets, a centrifuge injector was developed for ASDEX Upgrade based on a novel acceleration scheme, the stop cylinder principle [1]. Showing advantageous performance at ASDEX Upgrade, this scheme was adopted for the construction of similar injectors for JET and JT-60U. However, the bigger plasma volume in both tokamaks required an enhanced pellet particle flux. Therefore, a pellet source using continuous ice extrusion was needed instead of a pre-filled storage cryostat to match the extended fuel consumption. Deuterium pellets have T ≈ 16 K when delivered directly by the extruders instead of T ≈ 12 K when fed from a storage cryostat. They are therefore subject to more gas repulsion. An extension to the original acceleration scheme adapting it to the changed conditions was developed at JET and is now also applied at the JT-60U injector. Both injectors are now capable of delivering pellets with almost the same characteristics as the ASDEX Upgrade centrifuge.
[1] C. Andelfinger, et al., Rev. Sci. Instr. 64(4), 983 (1993).