Hモード周辺プラズマの無次元量解析

Japan Atomic Energy Agency

浦野　創

原子力機構那珂核融合研究所

CorePerformance

CoreProfile

PedestalTPED, nPED

Core EdgePedestal

sepa

ratr

ix

Divertor

ELM

Shoulder

H-mode is considered as the standard operation mode in ITER.

1. Steady state with the existence of ELM accompanied by pulsating expulsion of heat and particle.

2. Favorable confinement due to edge transport barrier

Pedestal characteristics can strongly be linked to

1. Boundary condition determining the core energy confinement

2. Characterization of ELM losses

Introduction

width

Dimensionless analysis on spatial width of H-mode pedestal

Optimizing pedestal width ped and height is a crucial issue to control the overall H-mode confinement. Dimensionless analysis is urgent issue for extrapolation to ITER.

This is because a strong co-linearity between and is hard to separate out at the plasma edge.

ped expressed by non-dimensional parameters are not consistent among several devices.

F(, q, , , , …)=ped

Examine the scaling of pedestal width by conducting the non-dimensional transport experiment introducing hydrogen discharges.

Co-linearity between and at the plasma edge in the H-modes

Dependence of pped on Ip yields and * as a function of Ip at * = const.

const.T/n 2 const.T/n 2

This co-linearity is hard to separate in the H-mode plasmas only with a single species.

ITn Ip1.0-1.5Tn

Japan Atomic Energy Agency, Naka Fusion Institute JT-60U Tokamak: p. 5

Examine dependence on introducing hydrogen plasmas

CONDITION: IP~1MA, BT~2, DELTA~0.3

Examine the dependence of ped on or while keeping total pol fixed in hydrogen and deuterium H-modes.

(1) If PED , spatial profiles would deviate by m0.5.

(2) If PED , spatial profiles would be similar.

Similar profiles are obtained in H/D plasmas. This result implies * dependence is weak.

(H. Urano, et al., NF 48 (2008) 045008)

Power scan of satisfying = const. in H/D plasmas reveals the ( m0.5) dependence of ped at fixed density.

Experiments on dependence of ped

[MW

]

15

0

[101

9 m-3

]

3.5

01.5

0

[MJ]

[a.u

.]

2

01.5

012 13 14

[MW

]

15

0

[101

9 m-3

]

3.5

01.5

0

[MJ]

12 13 14 15

[a.u

.]

2

01.5

0

PNBI

ne

DD

Wdia

pol

PNBI

ne

Wdia

pol

Deuterium Hydrogen

0

2

12.1 12.512.1 12.5 14.2 14.614.2 14.6

time [sec] time [sec]

D

[a.u

.]

D

[a.u

.]

0

2

fELM ~ 55Hz100 ms 100 ms fELM ~ 150Hz

Ip = 1.08 MA, BT = 2.4T = 0.35

Power required to sustain the same in H-plasma is ~2 times larger than that in D-plasma.

Higher ELM frequency is observed in H-plasma.

0

1

2

3

4

0 10 1r/a

ne

[101

9 m-3

]

0

1

2

3

4

0

1

2

3

4

0 10 1r/a

Te

[keV

]

0

1

2

3

4

0

1

2

3

4

0 10 1r/a

Ti[k

eV]

HD

10-1

0.6 110-3

10-2

10-1

1

10-1

1

10

10-2

r/a 0.6 1r/a 0.6 1r/a

pol

*

pol

*D

H

0

1

2

3

4

0 10 1r/a

ne

[101

9 m-3

]

0

1

2

3

4

0

1

2

3

4

0 10 1r/a

Te

[keV

]

0

1

2

3

4

0

1

2

3

4

0 10 1r/a

Ti[k

eV]

HD

10-1

0.6 110-3

10-2

10-1

1

10-1

1

10

10-2

r/a 0.6 1r/a 0.6 1r/a

pol

*

pol

*D

H

10-1

1

10

10-2

r/a 0.6 1r/a 0.6 1r/a

pol

*

pol

*D

H

Similar profiles of ne, Te, Ti were obtained in H/D plasmas.

Thus, mass effect clearly appeared in the profiles ( m0.5) while the profiles of and were similar.

*

0

1

2

3

4

5

0 0.1 0.2 0.3 0.40 0.1 0.2 0.3 0.4 p

ol

[10

-2]

pol

D

H

0.02

0.2

0.8 1 2 4 8

pe

d/ a

p

pol [10-2]

0

1

4 4.1 4.2 4.3 4.4

shoulder

R [m]

Ti[k

eV]

separatrix

0

1

4 4.1 4.2 4.3 4.44 4.1 4.2 4.3 4.4

shoulder

R [m]

Ti[k

eV]

separatrix

6

0.1

D

H = 0.1

D

H = 0.1

Despite of different at the pedestal by mass ratio (~ 1.4), the similar edge profile are obtained in H/D plasmas.

In a series of experiments, change of ped is small in the variation of pol at fixed pol (ped ap 0.2).

= 0.2

Experiments on pol dependence of ped

Power scan of satisfying pol Ip4 at the pedestal with controlling n Ip

4 gives the variation of pol at fixed pol.

time [sec] time [sec]

PNBI

ne

D

Wdia

pol

PNBI

ne

Wdia

pol

[MW

]

25

0

[101

9 m-3

]

3.5

03.0

0

[MJ]

[a.u

.]

2

01.5

0[M

W]

25

0

[101

9 m-3

]

3.5

03.0

0[M

J]

[a.u

.]

2

01.5

07 8 9 10 11 1210 13 14

0.96MA/2.1T high pollow pol 1.15MA/2.5T

Case A Case B

Compare profiles at time slices when pol* remains constant at the pedestal.

0

1

2

3

4

5

0 10

1

2

3

4

0 10

2

4

6

0 1

ne

[101

9 m-3

]

r/a

Te

[keV

]

r/a

Ti[k

eV]

r/a

Case B

Case A

10-2

10-1

0.6 1 0.6 110-2

1

10-1

pol pol

0.6 1

10-1

10-2

1

Case B

Case A

0

1

2

3

4

5

0 10 10

1

2

3

4

0

1

2

3

4

0 10 10

2

4

6

0 10 1

ne

[101

9 m-3

]

r/a

Te

[keV

]

r/a

Ti[k

eV]

r/a

Case B

Case A

10-2

10-1

0.6 10.6 1 0.6 10.6 110-2

1

10-1

pol pol

0.6 10.6 1

10-1

10-2

1

Case B

Case A

In the peripheral region, is varied while keeping and fixed.

*

When ( T0.5/Ip) remains constant at the pedestal, ped becomes wider at higher pol plasma.

Appropriate power scan gives a data set with the variation of . Then, the relation of ped ap 0.5 is obtained.

0.02

0.04

0.06

0.080.1

0.2

0.1 0.2 0.4 0.60.8

pol

pe

d/a

p

= 0.5

Scaling of pedestal width

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

0.315 pol0.2 pol0.5

ped

/ a p

D

H

Based on the non-dimensional transport experiments using H/D plasmas, the scaling on H-mode pedestal width is obtained

Rho dependence of the pedestal width is weak while it depends strongly on beta.

ped ap 0.2 0.5ped ap

Summary

Conducting the H-mode experiments using hydrogen (H) and deuterium (D) discharges, dependence of pedestal width on non-dimensional parameters were examined.

Similar pedestal profiles were obtained at H/D plasmas. When is raised, pedestal width increased with a relation expressed as ped ap 0.2 0.5.