Density profiles of H-mode plasmas in JT-60U

H. Takenaga, H. Urano, N. Oyama

JAERI, Naka

Acknowledgment : S. Watanabe (Kyoto University)

8th Meeting of the ITPA Confinement Database & Modeling Topical Group18-21 April, 2005

Kyoto University, Kyoto, Japan

OutlineJT-60U

Introduction

Density profile in NB heated H-mode plasmasHigh configurationLow configuration

Density profile in ECH H-mode plasmas

Summary

IntroductionJT-60U

Density profile in a fusion reactor ?

Peaked profileHigh fusion outputImpurity accumulation

Flat profileNo or small impurity

accumulationLow fusion output

Anomalous inward pinch Low central fueling

ASDEX-U, JET : density peaking factor increased with decreasing the effective collisionality (eff).

eff=ei/De : De is the curvature drift frequency

?

What is the mechanism determining the density profile ?

C. Angioni et al., Phys. Plasmas 10 (2003) 3225.H. Weisen et al., 20th IAEA Fusion Energy Conference (2004, Vilamoura) EX/P6-31.

NB heated H-mode database

1

1.2

1.4

1.6

1.8

2

2.2

2.4

0.3 0.4 0.5 0.6 0.7ne/nGW

JT-60UIp=1.0 MA, BT=2-2.1 T, Pabs=8-10 MW, ne/nGW=0.3-0.7High : =0.4-0.5, Low : =0.2-0.3

H89PL is larger in high than in low for ne/nGW<0.6.

High

Low

0.1 1

eff / =0.5@r a

Density peaking factor tends to increase with decreasing the effective collisionality.

JT-60U

eff~0.1RZeffne/Te2

But, data are scattered in low eff region.No clear dependence on .Dependence of density peaking factor on eff is similar

to that in ASDEX-U and JET.

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

1.5 2 2.5 3 3.5 4ne (10

19 m

-3)

Density profile peaking accompanies with temperature profile peaking.

JT-60U

ne (1019 m-3) Te (keV) Ti (keV)

0

0.5

1

1.5

2

2.5

3

3.5

0 0.2 0.4 0.6 0.8 1r/a

0

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1r/a

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8 1r/a

E037843, 8.9sE041544, 3.585s

E037843, 8.9s

H89PL=1.9, ne/nGW=0.40E041544, 3.585s

H89PL=1.5, ne/nGW=0.43

Density peaking seems to be correlated with confinement improvement.

Data and fitting qualities should be checked in future work.

0.1 11.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

eff / =0.5@r a

Density peaking seems to be correlated with ion temperature peaking.

JT-60U

eff<0.4

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7T

e(r/a=0.2)/<T

e>

2 2.2 2.4 2.6 2.8 3 3.2T

i(r/a=0.2)/<T

i>

eff<0.4

Correlation between density peaking and electron temperature peaking is not clear.

0

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1r/a

ECH H-modeJT-60U

00.20.40.60.8

1

01234

0

1

2

3

01234

9.5 10 10.5 ( ) TIME s

0

0.5

1

1.5

2

2.5

3

3.5

0 0.2 0.4 0.6 0.8 1r/a

ne (1019 m-3) Te (keV)

H-mode

L-mode

L-mode H-modeE041498

Type I ELMy H-mode plasma with 2nd harmonic X-mode ECH without central fueling.

H89PL=1.4 at ne/nGW~0.6 with PEC~3 MW.

Ip=1.1 MA, BT=2.0 TCenter EC Wave deposition

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

1.5 2 2.5 3 3.5 4ne (10

19 m

-3)

ECH H-mode has a similar density peaking factor to that in NB H-mode.

JT-60U

ECH H-mode

0.1 1eff / =0.5@r a

ECH H-mode

Absence of central fueling does not significantly affect the density profile.

SummaryJT-60U

Density profiles are investigated in NB and ECW heated H-mode plasmas.

The density peaking factor tends to increase with decreasing the effective collisionality, but data are scattered in low collisionality region.

One of the reasons for scattering of the data could be different confinement. The density peaking factor seems to be correlated with the ion temperature peaking factor. Data and fitting qualities should be checked in future work.

ECH H-mode has a similar density peaking factor to that in NB heated H-mode, indicating small effects of the central fueling.