Bestimmung der Speziesverteilung H$^{+}$, H$^{+}_{2}$ und H$^{+}_{3}$ in der Ionenquelle für die Neutralteilchen-Injektoren an Textor

Abstract

The ion species fractions H$^{+}$, H$^{+}_{2}$ and H$^{+}_{3}$ in the extracted beam of an ion source for neutral beam injection are detennined. Optical rneasureruents are obtained frorn a grating spectrometer using Dopplershifted H$_{\alpha}$ -light of the extracted beam and are compared to measurements with a magnetic spectrometer at the end of the beam line. The plasma source is a bucket source (modified JET-PINI) with a multiple magnetic field in checkerboard arrangement. The measurernents were performed on the multimegawatt beam line of the IPP NI - testfacility at KFA Jülich. The species fractions obtained for beams at 50 kV, 85 A, 4.25 MW are 63.8 : 24.5 : 11.7% (H$^{+}$ : H$^{+}_{2}$ : H$^{+}_{3}$). Measurements over the beam pulse length of 2.6 sec show no significant variation of the extracted species mix with pulse length