xp 505: the dependence of power threshold on dr sep and x-point height

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

XP 505: The dependence of power threshold XP 505: The dependence of power threshold on dron drsepsep and X-point height and X-point height

Hendrik MeyerHendrik MeyerEURATOM/UKAEA Fusion, UKEURATOM/UKAEA Fusion, UK

Rajesh MaingiRajesh MaingiOak Ridge National Laboratory, USAOak Ridge National Laboratory, USA

Ted BiewerTed BiewerMassachusetts Institute of Technology, USAMassachusetts Institute of Technology, USA

Hendrik MeyerHendrik MeyerEURATOM/UKAEA Fusion, UKEURATOM/UKAEA Fusion, UK

Rajesh MaingiRajesh MaingiOak Ridge National Laboratory, USAOak Ridge National Laboratory, USA

Ted BiewerTed BiewerMassachusetts Institute of Technology, USAMassachusetts Institute of Technology, USA

ResearchSupported by

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

Improved H-mode access in DNImproved H-mode access in DN

Motivation:Motivation: PPthrthr reduced by factor 2 in reduced by factor 2 in

C-DN on MAST (NSTX similarity shape).C-DN on MAST (NSTX similarity shape). 20 % of 20 % of PPthrthr reduction in C-DN on AUG. reduction in C-DN on AUG. Results on NSTX in 2004 suggested similar Results on NSTX in 2004 suggested similar

effect.effect.

[1] Meyer et.al., PPCF 47 p843 (2005)[2] Meyer et.al., NF to be publ. In Dec. 2005

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

EErr more negative in C-DN (L-mode) more negative in C-DN (L-mode)

SOL flow pattern sets-up ESOL flow pattern sets-up Err in during L-mode. in during L-mode. B2SOLPS5.0 simulations [IAEA TM H-mode].B2SOLPS5.0 simulations [IAEA TM H-mode]. Changes on HFS more pronounced than on LFS.Changes on HFS more pronounced than on LFS.

Agreement with MAST and AUG data.Agreement with MAST and AUG data.

SOL flow pattern sets-up ESOL flow pattern sets-up Err in during L-mode. in during L-mode. B2SOLPS5.0 simulations [IAEA TM H-mode].B2SOLPS5.0 simulations [IAEA TM H-mode]. Changes on HFS more pronounced than on LFS.Changes on HFS more pronounced than on LFS.

Agreement with MAST and AUG data.Agreement with MAST and AUG data.

DN-LDN-Crrr EEE

from from toroidal toroidal HeHe++ velocityvelocity

MASTMAST

from from Doppler Doppler reflectometreflectometryry

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

Goals of XPGoals of XP

Measure PMeasure Pthrthr in DN, L-SN, and U-SN with NBI in DN, L-SN, and U-SN with NBI heating.heating.

Compare PCompare Pthrthr with RF and NBI heating with RF and NBI heatingEffect of momentum input.Effect of momentum input.

Measure edge rotation and edge profiles before Measure edge rotation and edge profiles before and after the L/H transition.and after the L/H transition.

Measure PMeasure Pthrthr with different heights of X-point in with different heights of X-point inL-SN.L-SN.

Measure PMeasure Pthrthr in DN, L-SN, and U-SN with NBI in DN, L-SN, and U-SN with NBI heating.heating.

Compare PCompare Pthrthr with RF and NBI heating with RF and NBI heatingEffect of momentum input.Effect of momentum input.

Measure edge rotation and edge profiles before Measure edge rotation and edge profiles before and after the L/H transition.and after the L/H transition.

Measure PMeasure Pthrthr with different heights of X-point in with different heights of X-point inL-SN.L-SN.

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

Lowest PLowest Pthrthr in DN ― highest in U-SN in DN ― highest in U-SN

NBI heated:NBI heated: IIpp= 0.6 MA, B= 0.6 MA, Btt = 0.45 T = 0.45 T

RF heated:RF heated: IIpp = 0.6 MA, B = 0.6 MA, Btt = 0.45 T = 0.45 T

PulsePulse Conf.Conf.drdrsepsep

[mm][mm] uu ll PPNBINBI [MW] [MW]

117752117752 DNDN 00 2.02.0 0.490.49 0.470.47 0.60.6

117747117747 L-SNL-SN -20-20 1.761.76 0.350.35 0.520.52 1.11.1

117750117750 U-SNU-SN 1414 1.721.72 0.550.55 0.350.35 4.04.0

PulsePulse Conf.Conf.drdrsepsep

[mm][mm] uu ll PPRFRF [MW] [MW]

117767117767 DNDN 00 1.981.98 0.490.49 0.480.48 0.60.6

117776117776 DNDN 00 1.971.97 0.500.50 0.470.47 1.11.1

117777117777 L-SNL-SN -5-5 1.891.89 0.360.36 0.450.45 1.7 – 2.21.7 – 2.2

117782117782 L-SNL-SN -17-17 1.861.86 0.270.27 0.450.45 2.72.7

Ohmic:Ohmic: IIpp = 0.9 MA, B = 0.9 MA, Btt = 0.45 T, -24 mm < dr = 0.45 T, -24 mm < drsepsep < 0 (117754, 117756) < 0 (117754, 117756)

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

Sharp transition in L-SN and U-SN (NBI)Sharp transition in L-SN and U-SN (NBI)

#117752@0.24#117747@0.24#117750@0.24

#117752#117752#117747#117747#117750#117750

#117752#117752#117747#117747#117750#117750

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

PPthrthr increases with dr increases with drsepsep (RF) (RF)

#117776#117777#117782

#117776@0.3#117777@0.3#117782@0.3

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

Results SummaryResults Summary

Local minimum of PLocal minimum of Pthrthr in C-DN. in C-DN.

PPthrthr 4 times higher in U-SN than in L-SN. 4 times higher in U-SN than in L-SN. Similar to conventional tokamaks.Similar to conventional tokamaks. First H-mode in U-SN in an ST.First H-mode in U-SN in an ST.

Similar behaviour with RF heating.Similar behaviour with RF heating. PPthrthr seems to increase with RF shot history (impurities?) seems to increase with RF shot history (impurities?)

PPthrthr increases with dr increases with drsep sep in L-SN.in L-SN.

Local minimum of PLocal minimum of Pthrthr in C-DN. in C-DN.

PPthrthr 4 times higher in U-SN than in L-SN. 4 times higher in U-SN than in L-SN. Similar to conventional tokamaks.Similar to conventional tokamaks. First H-mode in U-SN in an ST.First H-mode in U-SN in an ST.

Similar behaviour with RF heating.Similar behaviour with RF heating. PPthrthr seems to increase with RF shot history (impurities?) seems to increase with RF shot history (impurities?)

PPthrthr increases with dr increases with drsep sep in L-SN.in L-SN.

NSTX Research Forum, 12 - 16 Dec. 2005, PPPLNSTX Research Forum, 12 - 16 Dec. 2005, PPPL

Steps towards publicationSteps towards publication Compare net power rather then injected power.Compare net power rather then injected power.

Compare edge TCompare edge Tee, n, nee and T and Tii evolution through the L/H evolution through the L/H transition.transition.

Comparison with L/H threshold theories.Comparison with L/H threshold theories. Compare ECompare E££B shearing rate with linear growth rate of B shearing rate with linear growth rate of

fluctuations.fluctuations.

Compare net power rather then injected power.Compare net power rather then injected power.

Compare edge TCompare edge Tee, n, nee and T and Tii evolution through the L/H evolution through the L/H transition.transition.

Comparison with L/H threshold theories.Comparison with L/H threshold theories. Compare ECompare E££B shearing rate with linear growth rate of B shearing rate with linear growth rate of

fluctuations.fluctuations.