Charge-exchange spectroscopy at the W7-AS stellarator employing a high-energy Li beam
H Ehmler; J Baldzuhn; K McCormick; A Kreter; T Klinger; W7-AS Team
Журнал:
Plasma Physics and Controlled Fusion
Дата:
2003-01-01
Аннотация:
Combined measurements of ion density, temperature and poloidal rotation of impurity ions have been carried out in the gradient region of the Wendelstein 7-AS plasma, employing charge-exchange spectroscopy with the high-energy neutral Li beam and C<sup>6+</sup>/C<sup>5+</sup> ions. The present state of the experimental technique is described. Results are obtained in discharges with high central ion temperatures of 1.3 keV, central electron densities of 7×10<sup>19</sup> m<sup>−3</sup>. Under these conditions the diagnostic covers a region of about 7 cm radial extent, corresponding to ion temperatures between 50 and 800 eV. Poloidal rotation velocities up to (35±2.5) km s<sup>−1</sup> were measured in a narrow shear layer at the plasma edge. The contribution of ion diamagnetic and E×B drift is discussed. The radial electric field is derived from a simplified radial force balance equation.
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