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Monday Physics Meeting, 05/05/083 Fast probe vs TS measurement Both diagnsotics are well validated against each other Fast probe data in FY08: limited due to some technical difficulties (eg, Low power H-mode access, LCFS position control, tip arcing, etc) Use TS data to complement probe data
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Monday Physics Meeting, 05/05/08 1
XP-815 – Characterization of divertor heat flux width and mid-plane SOL widths
J-W. Ahn1, R. Maingi2, J. Boedo1, V. Soukhanovskii3, R. Maqueda4, S. Zweben5
1University of California – San Diego
2Oak Ridge National Laboratory
3Lawrence Livermore National Laboratory
4Nova Photonics
5Princeton Plasma Physics Laboratory
Monday Physics Meeting, 05/05/08 2
Motivation and goals of the experiment
Topics of investigation in FY08 (all in H-mode)
(1) To find dependence of λq (target), λTe and λne (upstream) on plasma parameters (Ip, nebar and Power)
(2) To develop SOL width scalings(3) To find the relation between SOL widths and the edge
turbulence characteristics
Monday Physics Meeting, 05/05/08 3
Fast probe vs TS measurement
Both diagnsotics are well validated against each other Fast probe data in FY08: limited due to some technical difficulties (eg, Low power H-mode access, LCFS position control, tip arcing, etc)
Use TS data to complement probe data
Monday Physics Meeting, 05/05/08 4
Ip scan result 1 – Fast probe Te and ne decay lengths
0
5
10
15
20
25
30
35
0 2 4 6 8 10 12 14
machfit2_midmap_128794_man_lrdfit04Ip=1.0MA, NBI=1.4MW, Te=0.7cmIp=0.8MA, NBI=1.4MW, Te=1.3cm
Te (e
v)
R-Rsep midplane (cm)
0
0.5
1
1.5
2
2.5
0 2 4 6 8 10 12 14
Ip=1.0MA, NBI=1.4MW, ne=1.1cmIp=0.8MA, NBI=1.4MW, ne=0.94cm
ne (1
e13
cm-3
)
R-Rsep midplane (cm)
1MA 0.8MA: Te increases by a factor of ~2 but λne unchanged: λq also increases by a factor of ~2 (0.9cm vs 1.6cm)therefore, λTe dominates λq??
Monday Physics Meeting, 05/05/08 5
Ip scan result 2 – IR heat flux decay lengths
1MA 0.7MA: q increases by more thana factor of 2 Fast probe Te and ne data incomplete use TS data
Monday Physics Meeting, 05/05/08 6
Ip scan result 3 – TS profiles
TS profiles seem to indicate: Ip↓ λTe↑ & λne unchanged However, TS data points too sparse, does not allow for scale length fitting To Ensemble TS data points as a function of R-Rsep
Monday Physics Meeting, 05/05/08 7
Ip↓ λTe↑ & λne unchanged consistent with fast probe result
Ip scan result 4 – λTe & λne from TS data
Monday Physics Meeting, 05/05/08 8
Density scan result 1 – λq unchanged with <ne> ↑
nebar increase by ~40% λq stays remarkably similar Fast probe data does not show consistent trend
0
0.5
1
1.5
2
0 2 4 6 8 10 12 14
machfit2_midmap_128340_man_lrdfit04
128340, <ne>=3.8e13cm-3, ne=0.8cm128339, <ne>=4.3e13cm-3, ne=1.0cm128338, <ne>=4.8e13cm-3,ne=1.4cm128342, <ne>=4.6e13, ne=0.6cm
Den
sity
(1e1
3cm
-3)
R-Rsep midplane (cm)
Monday Physics Meeting, 05/05/08 9
Density scan result 2 – TS profiles
Although some decay length variation seen, no consistent tendency is observed
Monday Physics Meeting, 05/05/08 10
Density scan result 3 – λTe & λne from TS data
Considering the uncertainty of R-Rsep for each TS profile, therefore responsible for the data scatter of the ensembled TS data, λTe and λne seem to stay unchanged with nebar increase from 4.1 to 5.6e13
Monday Physics Meeting, 05/05/08 11
Power scan result 1 – λq↓ with Power ↑
PNBI↑ λq ↓ No fast probe data obtained for power scan
Monday Physics Meeting, 05/05/08 12
PNBI↑ λTe ↓ & λne unchanged
Power scan result 2 – λTe & λne from TS data
Monday Physics Meeting, 05/05/08 13
Ip, nebar, and Power scan to confirm dependence of λq, λTe, and λne were completed
λq data robust λTe and λne data from fast probe + TS
λq has a strong dependence on Ip (-) and power (-) nebar does not affect any scale length λq variation primarily comes from λTe λne seems unchanged by any parameter scan
Summary and future work
More data point and confidence SOL Scaling Relation between SOL widths and the edge turbulence characteristics Analysis of GPI data and probe Isat data underway