Aachen PK 2003 – wissenschaftliches Programm
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P: Plasmaphysik
P 4: Poster I
P 4.23: Poster
Montag, 17. März 2003, 17:45–19:15, Foyer
Development of the diagnostic neutral beam injector for Wendelstein 7-X — •A Kreter1, J Baldzuhn2, V I Davydenko3, A A Ivanov3, T Richert2, B Schweer1, and R Uhlemann1 — 1Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, Trilateral Euregio Cluster, EURATOM Association, 52425 Jülich, Germany — 2Max-Planck-Institut für Plasmaphysik, EURATOM Association, 17491 Greifswald, Germany — 3Budker Institute of Nuclear Physics, Prospect Lavrentieva 11, 630090 Novosibirsk, Russia
The Diagnostic Neutral Beam Injector (DNBI) is a tool for local measurements of the ion energy distribution, plasma rotation, impurity densities or H/D ratio by means of neutral particle analysis (NPA) and charge-exchange recombination spectroscopy (CXRS). Both systems are included in the diagnostic concept for the stellarator W7-X. A hydrogen beam with an equivalent neutral current of 5 A at an accelerating voltage of up to 60 kV and a pulse duration of 5 s every 2 min is requested to fulfill the requirements of NPA and CXRS for W7-X. A long-term objective is a continuously working (cw) beam. The ongoing development of DNBI is based on experience gained with the rf ion source DNBI at the tokamak TEXTOR (1 A, 50 keV, 5 s/5 min), which will be scaled-up to increase the current. The geometry of the four-grid acceleration system will be optimized to reduce the divergence to 0.3−0.4o. For the cw beam, several schemes of the water-cooled grids are under consideration. To improve the species distribution a test of a cold cathode arc discharge ion source is scheduled on TEXTOR. A full energy fraction of >80 % has been achieved in first tests for the subsecond pulse operational mode.