report on xp517: study of tae stability vs. q shear and q(0)
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Report on xp517: Study of TAE stability vs. q shear and q(0). E. D. Fredrickson PPPL, Aug. 8, 2005. Quick Summary of Status. Variations in beam injection time did result in "control" of q(0). TAE/EPM activity showed changes correlated with variation of q(0). TAE at high q(0), EPM at low. - PowerPoint PPT PresentationTRANSCRIPT
Report on xp517:Study of TAE stability vs. q shear and q(0)
E. D. FredricksonPPPL, Aug. 8, 2005
Quick Summary of Status• Variations in beam injection time did result in
"control" of q(0).– TAE/EPM activity showed changes correlated
with variation of q(0).– TAE at high q(0), EPM at low.
• Maintaining L-mode without He puffing was difficult.– Soft x-ray emissivity was low in L-mode plasmas.– Secondary goal of documentation of internal
amplitude and structure was poorly realized.
Limiter plasmas used to stay in L-mode• Soft x-ray diagnostic measures EPM amplitude.• So far, TAE not seen in SXI or Firetip
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• Strong TAE often with mild shear reversal.
• EPMs at lower q(0).
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q(0) ≈ 1;classic fishbones
• Large variation in neutron rate response; evolution in fast ion distribution or in mode structure?
• Virtually no TAE activity (with 3 neutral beam sources).
At higher q(0),cw EPMs
• EPMs still n=1; infernal fishbones?
• Convert to saturated EPMs later - possibly correlated with higher q?
• Internal diagnostics include soft x-rays and Firetip.
• Weak TAE activity earlier (1 source).
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Firetip/sxi can detect EPMs
• Important to have some internal, direct, measure of mode amplitude.
• Soft x-rays can also provide information on mode structure.
• Earlier chirps (0.28 & 0.3s) apparently weaker than cw mode; similar amplitude for B.
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Moderate q(0), H-mode:
mixed TAE/EPM• May also be some density,
density profile dependence for TAE.
• "H-mode onset" about 210 ms.– Weak soft x-ray emission– Reflectometers looking near
plasma edge.• May not be enough data.
High q(0); TAE-like modes
• This shot was anomaly, slow current penetration even with late beam injection.
• L-mode density profile means potentially useful reflectometer data.
• TAE still chirping, maybe more like rTAE.
High q(0):TAE or rTAE
• TAE-turbulence• Chirping modes at TAE
frequencies suggest resonant TAE, rTAE.
• Large neutron drop correlated with EPM; TAE seem to usually have small impact on fast ion confinement.
TAE not seen with Firetip or
sxi• Mode amplitude
probably too small (probably not chord-integration cancellation).
• May provide upper limit on amplitude…
Density profile looks good for reflectometer data
• Stays in L-mode with three sources.• Weak central shear reversal in this shot.
0.000.050.100.150.200.2550100150BCDEEBDEFFBEGHBDFGHBDFGBDEFGBDDCBBBBBB CONTOURS: n/cm**3 A = 0.0000E+00 B = 5.0000E+12 C = 1.0000E+13 D = 1.5000E+13 E = 2.0000E+13 F = 2.5000E+13 G = 3.0000E+13 H = 3.5000E+13 J = 4.0000E+13 K = 4.5000E+13 L = 5.0000E+13 M = 5.5000E+13 N = 6.0000E+13 P = 6.5000E+13 Q = 7.0000E+13 R = 7.5000E+13 S = 8.0000E+13secondscmElectron Density VS time & radiusnstx 116911 page 2
• Inner reflectometer channel in low q-shear region.
• Haven't looked at data yet.
Future work
• Finish sorting and categorizing.• Check out reflectometer data.• TRANSP runs to find fast ion distributions.• Input to M3D, Nova, etc.
q(0) ≈ 1;Classic fishbones?• TAE present, but weak.• Fishbone becomes a
saturated EPM; consistent with theoretical models and seen previously at high aspect ratio.
• Possibly sawteeth later.