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Multi-view fast-ion D-alpha spectroscopy diagnostic at ASDEX Upgrade
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View: Figures


Image of FIG. 1.
FIG. 1.

Top-down (a) and a poloidal view (b) on the LOS-setup of the FIDA diagnostic at ASDEX Upgrade. The toroidal LOS are indicated in blue color and the poloidal ones are shown in purple. The MSE LOS is plotted in green. The NBI source Q3, which is used as a diagnostic beam, is sketched in orange and the separatrix position is illustrated by red, dashed lines.

Image of FIG. 2.
FIG. 2.

Radial resolution of three lines of sight of the FIDA diagnostic, based on the calculated neutral density present along the path of NBI Q3.

Image of FIG. 3.
FIG. 3.

Schematic top-down view on the FIDA spectrometer and camera setup.

Image of FIG. 4.
FIG. 4.

(a) Measured spectrum of the neon lamp between 655 nm and 668 nm. (b) Central wavelength on the CCD as a function of the channel's vertical position on the chip. A fit to the data with a parabola is shown in red.

Image of FIG. 5.
FIG. 5.

Passive spectra from a toroidal LOS (a) and a poloidal LOS (b) that were observed during (black) and after (gray) an ELM crash. In red, the theoretical shape of the D-alpha emission is plotted, demonstrating the presence of Stark broadening of this line.

Image of FIG. 6.
FIG. 6.

D spectra from a toroidal LOS, measured with (black) and without (gray) fueling from a proximate valve. In orange, tabulated molecular lines 25 are shown that correspond to = 3 → 2 transitions of the triplet system.

Image of FIG. 7.
FIG. 7.

Passive spectra from two toroidal LOS (a) and (c) and two poloidal LOS (b) and (d) in black that were acquired during off-axis NBI heating. In gray, active spectra are plotted that were acquired during the operation of NBI Q3.

Image of FIG. 8.
FIG. 8.

Characteristic time-traces of discharge #29578. From top to bottom, the plasma current and magnetic field, the NBI heating power, the electron density, and the ion and electron temperatures are plotted.

Image of FIG. 9.
FIG. 9.

Measured spectra on a semi-logarithmic scale from a toroidal LOS (a), a poloidal LOS (b), and the MSE LOS (c). In addition, the theoretical beam, halo, and FIDA components predicted by FIDASIM are plotted.

Image of FIG. 10.
FIG. 10.

TRANSP predicted velocity space distribution of fast ions in ASDEX Upgrade generated by NBI Q3 and a second 93 keV heating beam in discharge at 1.05 s.

Image of FIG. 11.
FIG. 11.

Synthetic FIDA spectra observed by a toroidal (blue), poloidal (purple), and the MSE (green) LOS for the two artificial fast-ion distributions sketched in Figure 10 in red and orange. (a) Spectra for pitches between 0.8 and 1.0. (b) Spectra for pitches between −0.1 and 0.1.

Image of FIG. 12.
FIG. 12.

Weight functions for a (a)–(c) toroidal, (d)–(f) poloidal, and the (g)–(i) MSE LOS for three different wavelength ranges. Depending on the wavelength, the LOS access different parts of the fast-ion velocity space.

Image of FIG. 13.
FIG. 13.

(a)–(i) Product of the fast-ion velocity distribution shown in Figure 10 with the weight functions displayed in Figure 12 .

Image of FIG. 14.
FIG. 14.

Temporal evolution of the FIDA intensities for three LOS and two wavelength ranges (a) and (b).

Image of FIG. 15.
FIG. 15.

Radial FIDA intensity profiles from the 7 toroidal LOS (blue) and 7 poloidal (purple) LOS that were connected to the FIDA spectrometer during discharge #29578. The error bars correspond to the fluctuation of the FIDA signal in the analyzed, 8 ms long, time interval.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Multi-view fast-ion D-alpha spectroscopy diagnostic at ASDEX Upgrade