Aachen PK 2003 – wissenschaftliches Programm
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P: Plasmaphysik
P 7: Plasma Diagnostics
P 7.2: Vortrag
Dienstag, 18. März 2003, 15:50–16:10, FO1
Spectroscopic measurements of the species fractions of the diagnostic hydrogen beam at the tokamak TEXTOR — •C Busch, D Geskus, A Kreter, B Schweer, and R Uhlemann — Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, Trilateral Euregio Cluster, EURATOM Association, 52425 Jülich, Germany
A diagnostic hydrogen beam (acceleration voltage Uacc=50 kV, ion current Ibeam=2 A) is used for the determination of the ion temperature, plasma rotation and impurity densities by means of charge-exchange recombination spectroscopy (CXRS) at the tokamak TEXTOR. The hydrogen ions H+, H2+ and H3+ produced in the ion source of the injector are extracted and accelerated by a four-grid ion-optical system. The dissociation and neutralization processes in the gas target result in neutral beam components with energies corresponding to full, half and one third of eUacc. The full energy component provides the strongest contribution to the CXRS signal intensity.
A new optical system has been designed in order to determine the species distribution by Doppler shift spectroscopy of the Hα beam emission. This system is prepared for the automatic intershot data analysis and contains a spectroscope equipped with a high speed linear photodiode array. The system has a spectral resolution of 0.25 nm and a variable frame rate of 10 - 3000 fps. The species fractions are deduced from the line intensities using a theoretical model for the processes occurring in the neutralizer [1]. The typical H+, H2+ and H3+ fractions in the rf ion source are 40 %, 30 % and 30 % respectively.
[1] Uhlemann R et al 1993 Rev. Sci. Instrum. 64 974