W7-AS contributions to the 11. topical conference ''High-temperature plasma diagnostics''. - W7-AS contributions to the 12. international conference on plasma surface interactions. - W7-AS contributions to the 23. EPS conference on controlled fusion and plasma physics

In the advanced stellarator W7-AS, active charge exchange recombination spectroscopy CXRS is performed on intrinsic plasma impurities. Measurements are done on the doublet lines of the singly charged species of He II, B V, C VI and N VII. A pulsed diagnostic neutral beam injector excites CX spectral lines in the visible or near UV region. By switching the beam off and on, the electron impact excited spectral light intensity from the cold plasma edge can be subtracted from the signal of interest. The spectral lines are observed after transmission by imaging mirrors and glass fibers by means of Czerny-Turner monochromators with high spectral resolution of down to 0.3 A per spectral channel. A turnable mirror device allows for the observation at well defined spatial locations within the plasma. As detectors, photomultiplier arrays and CCD camera systems are used. By spectral measurement of the CX Doppler line intensity, line shift and line broadening we evaluate the impurity density and rotation velocity profile and the impurity ion temperature. These parameters provide the transport relevant radial electric field and the ion temperature profile. The radial ion particle and heat transport together with the ambipolar electric field play a decisive role for the optimization of the 3-D stellarator plasma. (orig.)Available from TIB Hannover: RA 71(III/212) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman