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A model of the ion source designed for the neutral beam injectors of the International Thermonuclear Experimental Reactor (ITER), the KAMABOKO III ion source, is being tested on the MANTIS test stand at the DRFC Cadarache in collaboration with JAERI, Japan, who designed and supplied the ion source. Its target performance is to accelerate a D- beam, with a current density of 200 degree A/m2 and <1 electron extracted per accelerated D- ion, at a source pressure of 0.3 degree Pa. The performance of this ion source for long pulse operation is being studied at the MANTIS test stand at the DRFC, Cadarache, France.
Long pulse operation of the KAMABOKO III ion source has revealed three important problems: The negative ion yield is below that measured with short pulse operation (<5 degree s), the caesium consumption is more then 1000 times that expected for the source on the ITER neutral beam injectors, and the increase in negative ion yield is much less than measured with short pulses (<5 degree s). A detailed characterisation of this source has been carried out in an attempt to further understand the physics of negative ion formation in the source and to determine its most efficient operating conditions. This paper presents the results of the characterisation of the ITER design ion source and the diagnostics used, which include Langmuir probes for electron energy distribution measurements and the determination of other plasma characteristics, and optical emission spectroscopy. The Langmuir probe data can give information on the temporal behaviour of the plasma parameters and the spectroscopic measurements give information the behaviour of impurities and caesium as a function of time. In addition the spectroscopic data give the fractional dissociation of the H2, the H- density and the gas temperature. Both Langmuir probe and spectroscopic data have been obtained as a function of the source operating conditions.

Additional information

Authors: BOILSON D, Association EURATOM-DCU, PRL/NCPST, Glasnevin, Dublin (IE);DE ESCH H P L, Association EURATOM-DCU, PRL/NCPST, Glasnevin, Dublin (IE);HEMSWORTH R S, Association EURATOM-DCU, PRL/NCPST, Glasnevin, Dublin (IE);KRYLOV A, Association EURATOM-DCU, PRL/NCPST, Glasnevin, Dublin (IE);CROWLEY B, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);FANTZ U, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE);ZANIOL B, Associazione Euratom-ENEA sulla Fusione, Consorzio RFX, Padova (IT)
Bibliographic Reference: An oral paper given at: 11th International Conference on Ion Sources Organised by: GANIL, Caen (FR) Held at: Palais des congrès, Caen (FR)
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail:
Record Number: 200518355 / Last updated on: 2005-10-04
Original language: en
Available languages: en