Divertor Characteristics from Probe Measurements during NBI NSTX Results Review 26-28 July 2006 PPPL Princeton, NJ C.E. Bush a , R. Kaita b , P. Roney b , R. Maingi a , E.. Fredrickson b , S. Sabbagh c , V. Soukhanovskii d , J.G. Watkins e a Oak Ridge National Laboratory, Oak Ridge, TN USA b Princeton Plasma Physics Laboratory, Princeton, NJ USA c Columbia University, NY USA d Lawrence Livermore National Laboratory, Livermore, CA USA e Sandia National Laboratories, Albuquerque, New Mexico, USA Research Supported by
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Divertor Characteristics from Probe Measurements during NBI
Research Supported by. Divertor Characteristics from Probe Measurements during NBI. C.E. Bush a , R. Kaita b , P. Roney b , R. Maingi a , E.. Fredrickson b , S. Sabbagh c , V. Soukhanovskii d , J.G. Watkins e a Oak Ridge National Laboratory, Oak Ridge, TN USA - PowerPoint PPT Presentation
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Divertor Characteristics from Probe Measurements during NBI
NSTX Results Review 26-28 July 2006
PPPL Princeton, NJ
C.E. Busha, R. Kaitab, P. Roneyb, R. Maingia,
E.. Fredricksonb, S. Sabbaghc, V. Soukhanovskiid, J.G. Watkinse
aOak Ridge National Laboratory, Oak Ridge, TN USA bPrinceton Plasma Physics Laboratory, Princeton, NJ USA
cColumbia University, NY USAdLawrence Livermore National Laboratory, Livermore, CA USAeSandia National Laboratories, Albuquerque, New Mexico, USA
ResearchSupported by
C. Bush, ResultsRev_Jul2006 Page 2
Outline
•Initial NSTX Langmuir Probe System is a coarse array–Sample IV Characteristic data
•Langmuir Probe data obtained for vast majority of shots–Especially the last 3 campaigns–Data for many configurations–Data for many conditions
•Report Emphasizes a Beam Power Scan–Also a series of Gas Puff experiments
•Isat, Te reported for a limited set of experiments
•Summary
Backup Slides
END
The EFIT equilibrium shows the location of the inner and outer strike-points on the divertor plates of NSTX . In general the strike-points and measured probe positions are in good agreement.
Outer Strike-pointInnerStrike-point
LowerSingle-nullDivertor
C. Bush, ResultsRev_Jul2006 Page 4
Divertor Langmuir Probes
1234
1 R(probe 1) = 1.02 m2 R(probe 2) =
0.91 m3 R(probe 3) = 0.80 m4 R(probe 4) = 0.49 m
C. Bush, ResultsRev_Jul2006 Page 5
Fit to IV Characteristic for Flush Probe
Sweep voltage ± 50 volts
Only points V < VLimit included in fit.
Here VLimit = +15 V
The relatively flat upper part of curve due to 10 volt limit on digitizer not to electron current saturation.
* Te fit corrected for nonsaturationof ion current.Te = 6.72 eV(12 eV uncorrected).
Fit to IV data
Solid lines, data for
2 different sweeps
Isat(ion)
Probe sweep voltage
I
V
0
~Isat
I (A)
IV Characteristic
0.04
-0.04
0.08
0.12
-40 0 40
V (Volts)
14
C. Bush, ResultsRev_Jul2006 Page 6
Outer Divertor Probe Te vs Time, Pb = 4 MW
Shot 112498Pb = 4 MWRprobe = 0.91 m
C. Bush, ResultsRev_Jul2006 Page 7
Heat flux profile becomes more peaked with increasing NBI