Berlin 2001 – scientific programme
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P: Plasmaphysik
P 10: Theory and Plasma Diagnostic (Poster Session)
P 10.16: Poster
Wednesday, April 4, 2001, 12:30–15:00, AT2
High resolution spectroscopy of Hα at the T2R reversed field pinch. — •Frans Meijer1,2, Bob Gravestijn1, and Elisabeth Rachlew1 — 1Sect. of Atomic and Molecular Physics, Association EURATOM-NFR, Department of Physics, Royal Institute of Technology, KTH, SE 10044 Stockholm, Sweden — 2FOM-Instituut voor Plasmaphysics ’Rijnhuizen’, Nieuwegein, The Netherlands
We have studied the Hα emission from the T2R RFP with a 1.5 m Czerny-Turner spectrometer, equipped with a 1200 l/mm grating, using a linear array CDD camera with 2048 pixels, combined with an image intensifier. Recently, we reported on similar measurements from both the RTP tokamak at Rijnhuizen and at the T2 RFP. In both cases the light was collected along a tangential line-of-sight. The Hα lineshape could only be explained by assuming different groups of excited hydrogen atoms, each with its specific velocity distribution.
At T2R we now measure in a poloidal plane. Hα is mainly emitted from the outer region of the plasma, which means from a region where the magnetic field is mainly poloidal. We see now different components of this spectral line shifted in wavelength, whereas they in the toroidal measurements more or less coincided and showed only different widths. The linewidths differ also now. One component should originate from Franck-Condon dissociation of molecules released from the wall. The other could come from ionized hydrogen, neutralized by charge exchange and excited. More details will be presented at the conference.