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Beams, brightness, and background: Using active spectroscopy techniques for precision measurements in fusion plasma researcha)
a)Paper CT3 1, Bull. Am. Phys. Soc. 56, 58 (2011).
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10.1063/1.3699235
/content/aip/journal/pop/19/5/10.1063/1.3699235
http://aip.metastore.ingenta.com/content/aip/journal/pop/19/5/10.1063/1.3699235
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Components of a positive ion source-based hydrogen neutral beam injector for plasma heating. The same arrangement is used for deuterium () and tritium () as well as other non-hydrogenic beams.

Image of FIG. 2.
FIG. 2.

Basics of active spectroscopy. Emission from a small region of the neutral beam is imaged with collection optics and subsequently analyzed using a variety of spectroscopic techniques. The cross-beam view localizes the measurement.

Image of FIG. 3.
FIG. 3.

Dispersed spectral emission from charge exchange ion showing parameters used to infer moments of ion velocity distribution. Example shown is CVI line at rest wavelength of 5290 Å. Ion temperature is derived from the Doppler width w, the line-of-sight velocity is derived from the shift from the rest wavelength, and ion density is derived from the integral brightness .

Image of FIG. 4.
FIG. 4.

The charge exchange spectroscopy system on JET, circa 1993, illustrating key components for a successful measurement of impurity and main ion parameters. Reprinted with permission from von Hellermann et al., Plasma Phys. Controlled Fusion 35, 799 (1993). Copyright © 1993, IOP Publishing.

Image of FIG. 5.
FIG. 5.

Charge exchange cross-section for the CVI transition at with deuterium neutral in (a) ground state and (b) excited state. (c) Effective cross-section using calculated excited population (∼0.3%), with the only cross-section overplotted in gray for comparison. Reprinted with permission from Solomon et al., Phys. Plasmas 13, 056116 (2006). Copyright © 2006, American Institute of Physics.

Image of FIG. 6.
FIG. 6.

Results of a comprehensive fitting model for DIII-D spectrum which includes time-dependent collisional-radiative simulations, showing main ion charge exchange and fit corrections for fast ion slowing down, beam Stark multiplet, and edge line contributions. Reprinted with permission from Grierson et al., Rev. Sci. Instrum. 81, 10D735 (2010). Copyright © 2010, American Institute of Physics.

Image of FIG. 7.
FIG. 7.

Halo, edge line and beam emission dwarf FIDA signal. [Reprinted with permission from W. W. Heidbrink, Rev. Sci. Instrum. 81, 10D727 (2010). Copyright © 2010, American Institute of Physics.

Image of FIG. 8.
FIG. 8.

Example of beam emission spectra from 80 keV injection on DIII-D. Viewing obliquely at 57.3° yields approximately 30 Å Doppler shift for the full energy component. (a) Injection into helium fill gas with no fields shows the full, half, and third energy components, along with a small edge recycling line. (b) Expanded resolution for injection into deuterium plasma with fields reveals blended Stark multiplets plus the underlying high energy wing. Reprinted with permission from Pablant et al., Rev. Sci. Instrum. 81, 10D729 (2010). Copyright © 2010, American Institute of Physics.

Image of FIG. 9.
FIG. 9.

Components of a beam emission spectroscopy system designed for investigating high frequency density fluctuations on the DIII-D tokamak. Courtesy G. R. McKee (private communication).

Image of FIG. 10.
FIG. 10.

Stark-effect transitions and spectral pattern for the first Balmer line. The theoretical relative strength of each line component is indicated by length of the bar, with the weak components indicated by half circles. Adapted from E. U. Condon and G. H. Shortley, The Theory of Atomic Spectra (Cambridge University Press, Cambridge 1963), p. 401; and H. A. Bethe and E. E. Salpeter, Quantum Mechanics of One- and Two-Electron Atoms (Plenum Publishing, 1977), p. 232.

Image of FIG. 11.
FIG. 11.

Components of a motional Stark effect combined spectroscopy/polarimetry system designed for the JT-60U tokamak. Key elements are polarization maintaining optics including special lenses and mirrors, close control of the finite collection angle to minimize geometric Doppler broadening of the collected light, the use of photo-elastic modulators (PEMs) and linear polarizer to allow for lock-in detection of the polarization direction, and tilt- or thermally tuneable optical band-pass interference filter for isolation of one of the Stark components. Note, fast sampling allows for digital as well as analog demodulation of lock-in signals. Reprinted with permission from T. Suzuki, Rev. Sci. Instrum. 77, 10E914 (2006). Copyright © 2006, American Institute of Physics.

Image of FIG. 12.
FIG. 12.

(a) Zeeman effect transitions and spectral pattern for the lithium 2S-2P resonance line. (b) Triplet pattern at high field, , equivalent Doppler temperature is 1 eV. When viewed perpendicular to magnetic field, the lines are linearly polarized parallel to B and the sigma lines are linearly polarized perpendicular to B. When viewing parallel to B, the emission disappears and the sigma lines are circularly polarized Adapted from E. U. Condon and G. H. Shortley, The Theory of Atomic Spectra (Cambridge University Press, Cambridge, 1963), 149; and H. A. Bethe, E.E. Salpeter, Quantum Mechanics of One- and Two-Electron Atoms (Plenum Publishing, 1977), p. 205.

Image of FIG. 13.
FIG. 13.

imaging data from DIII-D discharge 135851 showing (a) 30 L beam off, (b) 30 L beam on, (c) panel (b) minus panel (a). Camera sampling rate was 900 frames s−1 and exposure time was 1.1 ms. Approximately, the top ten and bottom 30 rows of pixels are dark due to mechanical clipping of the FOV. “Counts” are out of 4096 set by camera dynamic range of 12-bits. Reprinted with permission from Van Zeeland et al., Plasma Phys. Controlled Fusion 52, 045006 (2010). Copyright © 2010, IOP Publishing.

Image of FIG. 14.
FIG. 14.

CAD model showing the relative layout of port plugs with some active spectroscopic optical systems. Shown are the planned core CXRS view from the upper port 03 viewing the core portion of the DNB trajectory, along with the CXRS/BES and MSE optics in equatorial port 03, which images the edge regions of the DNB and HNB5, respectively. An additional equatorial port plug 01 that provides core MSE views using the other heating beam HNB4 is not shown. Reprinted with permission from Thomas et al., Rev. Sci. Instrum. 81(10), 10D725 (2010). Copyright © 2010, American Institute of Physics.

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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Beams, brightness, and background: Using active spectroscopy techniques for precision measurements in fusion plasma researcha)
http://aip.metastore.ingenta.com/content/aip/journal/pop/19/5/10.1063/1.3699235
10.1063/1.3699235
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