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All figures (14)
Figure 4: Comparison of injected neutral density profile along the y and z axes from the FIDASIM code (symbols) and from TRANSP (lines) at the beam tangency point (R=70cm) for NSTX Source A.
Figure 5: Comparison between the FIDASIM and TRANSP simulations in NSTX discharge #122631 at t=0.1s. (a) Neutral density, (b) attenuation factor for 60 keV neutrals and (c) differential charge-exchange flux along the NPA sightline.
Figure 11: Vertical (y,z) planes of (a) injected neutral density near the plasma edge, (b) halo neutral density near the plasma edge, and (c) halo neutral density in the plasma interior.
Figure 10: (a) Midplane (z = 0) cross section of a quadrant of the DIII-D tokamak, showing the intersection of the vertical FIDA sightlines (triangles) and the (x,y) coordinate system associated with the active neutral beam. (b) Midplane halo neutral density. The distribution is asymmetrical due to the plasma flow. (c) Beam-ion density. (d) Injected neutral density.
Figure 14: (a) FIDA emissivity in an (x,z) plane, with the standard (33×21) grid boundaries overlaid. The red lines illustrate the range of sightline angles graphed in the lower figure. (b) Calculated radiance vs. sightline angle for different choices of grid size in the (x,z) plane. The flat portions of the curves are caused by pixelation.
Figure 12: Dependence of the calculated FIDA radiance on the volume of the simulation. The spectra are integrated over wavelengths above Eλ =10keV.
Figure 13: (a) Ratio of the blue-shifted FIDA radiance for simulations without halo neutrals and with halo neutrals vs. major radius. The spectra are integrated over wavelengths above Eλ = 10keV. (b) Ratio of the FIDA spectral radiance for simulations without halo neutrals and with halo neutrals for the FIDA channel at R=187.5cm. Two values of Eλ are indicated.
Figure 3: Solution of Eq. (2.3) immediately following neutralization of the fast ion for a typical case (density of 4×1013cm−3, temperature of 4keV). The total time represented by the abscissa is 11.1ns; the fast neutral travels 3cm during this time. The evolution of the n=3 state determines the intensity of FIDA light.
Figure 1: Flow diagram for the FIDASIM code.
Figure 8: (a) Comparison of FIDA spectra from simulations with 106 to 9×107 Monte Carlo particles. (The reduction in FIDA light for small Doppler shifts is an artifact caused by truncating the fast-ion distribution function at Emin = 10keV.) (b) FIDA spectra normalized to the spectrum computed with 90 million particles. The dashed vertical lines relate Doppler shifts to equivalent energies along the line-of-sight Eλ.
Figure 9: Comparison of FIDA profiles for simulations with 106 to 9×107 Monte Carlo particles. The spectra are integrated over Doppler shifts larger than (a) Eλ≥10keV and (b) Eλ≥30keV.
Figure 7: Comparison of halo neutral densities calculated from the 1-D diffusion model (Eq. (3.3)) and the FIDASIM halo diffusion subroutine for plasma profiles with ni=ne=1.1×1014cm−3, Te=2.5keV and Ti=1.25keV. The three dashed steps represent the densities of the full, half, and third energy components of injected neutrals used in both codes.
Figure 2: Plan view of NSTX. Geometrical neutral beam and detector input to the code is in (u,v,z) coordinates. Neutral beam parameters (upper case labels) follow the TRANSP conventions. The code transforms quantities into (x,y,z) coordinates along the selected beam.
Figure 6: NPA energy spectra for a sightline with Rtan = 70cm from the TRANSP and FIDASIM simulations with and without halos at three different times in NSTX discharge #122631. The density increased from approximately 2×1013cm−3 to 5×1013cm−3 between 0.1 and 0.5s.
Journal Article
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DOI
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A code that simulates fast-ion Dα and neutral particle measurements
[...]
William Heidbrink
,
D. Liu
,
Y. Luo
,
E. Ruskov
,
Benedikt Geiger
1
- Show less
+1 more
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Institutions (1)
Max Planck Society
1
01 Sep 2011
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Communications in Computational Physics