Southwestern Institute of Physics, Chengdu, China

Longwen Yan, Experimental Progress on HL-2A, 6-8 Jan. 2014, Tsinghua University, Beijing 1/29

HL-2A

Southwestern Institute of Physics, Chengdu, China

Experimental Progress on HL-2A

HL-2A Team (Presented by Longwen Yan)

The Second A3 Foresight Workshop on Spherical Torus


HL-2A

HL-2A tokamak

Diagnostic development

Confinement improvement and transport

Energetic physics and MHD activity

Turbulence and zonal flows

Summary

Outline


HL-2AHL-2A tokamak

•R: 1.65 m

•a: 0.40 m

•Bt: 2.7 T

•Ip: 450 kA

•ne: ~ 6.0 x 1019 m-3

•Te: ~ 5.0 keV

•Ti: ~ 2.8 keV

Auxiliary heating systems ECRH/ECCD: 3 MW: 60.5 MW/68 GHz/1 s 2 MW: 21 MW/140 GHz/3 s Modulated f=10~30 Hz; Amp. 10~100% NBI: 3 MW/55 kV/2 s (5 MW/80keV) LHCD: 2 0.5 MW/2.45GHz (2 MW/3.7GHz)

Fuelled system (H2/D2):

Gas puffing (LFS, HFS, divertor) Extruded PI (40 pellets/LFS, HFS) SMBI (LFS, HFS) LFS: f =10~60 Hz, pulse>0.5ms Gas pressure: 0.3-3.0 MPa HFS: f = 1-5 Hz, 0.2-1.0 MPa


HL-2A

HL-2A tokamak





Summary

Outline


HL-2AComparison of MSE spectral broadening

0.0

0.5

1.0

0.0

0.5

1.0

0.0

0.5

1.0

659.5 660 660.5 661 661.5 662 662.50.0

0.5

1.0

wavelength (nm)

Rel

ativ

e in

tens

ity (a

rb.u

nits

)

experimentfitting

experimentfitting

-

(a)

(b)

(c)

(d)

R=1.67m

R=1.67m#20239

R=1.95m

#20239

+

+ -

- +

+ -

R=1.95m

simulation

simulation Simulation parameters

• Beam dissipation d≈1.0° • Lens size=37mm • Energy dissipation dv=2%

Fitted functions

• I0 is intensity of central wavelength

0 is Stark splitting at central wavelength and σ is spectral width

2

20

2

)(

0)(

eII

Jiang N. et al 2013, CPL30, 065201


HL-2A

1.6 1.65 1.7 1.75 1.8-2

0

2

4

6

8

R (m)

Pit

ch a

ngle

(o )

t=420 mst=460 mst=500 ms

# 22196

Profiles of magnetic field pitch angle

Radial profiles of magnetic field pitch angles slightly increase with time, indicating current profiles to be peaking gradually


HL-2AFILD diagnostics successful on HL-2A

Shot 22614 Bt=1.34 TFrame f=500 fpsProbe at R=2.13 m

Current flattop during NBI Plasma disruption with NBI Flattop phase: Fast ion loss energy 40-50 keV

and pitch angle 630. Disruption phase: Fast ion loss energy and

pitch angle change with magnetic perturbation rather largely.


HL-2A

Pedestal structure during an ELM measured by a new microwave reflectometry with high spatiotemporal resolutions

Pedestal structure evolution during ELM


HL-2A

HL-2A tokamak





Summary

Outline


HL-2ABasis of confinement and transport

• Particle ITB observed in HL-2A for the first time (Xiao W. W. 2010, PRL. 104 215001)

• NLT effect induced by SMBI fuelling and ECRH switching off (Sun H.J. et al. 2010, PPCF 52 045003; Sun H.J. et al. 2012 NF 51, 113010)

• Turbulence and ELM characteristics (Duan X.R. 2010, NF 50, 095011; Yan L.W. 2011, NF 51 094016)

• ELM mitigation by SMBI/CJI fuelling succeeded on HL-2A for the first time, and confirmed by KSTAR and EAST (Xiao W. W. et al. 2012 NF52, 114027 )

• Duan X.R., NF 49 (2009) 104012

• Xiao W. W. 2010, PRL. 104 215001

• Zhong W.L., PoP 17, (2010)112307

• Liu Yi, PRE, 84 (2011) 016403

• Huang Y., NF 52 (2012)114008

20 25 30 350.8

1

1.2

1.4

1.6

1.8

2

r(cm)

ne(1

019

m-3

)

250ms420ms480ms520ms


HL-2A

140 160 180 2000

200

400

600

800

1000

1200

Ip(kA)

f EL

M(H

z)

w/o SMBIwith SMBI

HL-2A

ELM mitigated by SMBI successfully

3.5-2/ff 0ELM

SMBIELM

ne=1.8~2.3×1019m-3

Paux=0.9-1.4 MWXiao W. W. et al. 2012 NF52, 114027

Pedestal density gradient drops after SMBI fuelleing, indicating particle confiement degeneration

(a)


HL-2AELM mitigated by CJI better

2.2/ff 0ELM

CJIELM

0.38/II 0ave

CJIave Cluster jet injection

(CJI ） mitigates ELM instability with better effect than SMBI

1 1.5 2 2.5 3 3.50

0.2

0.4

0.6

0.8

1

f ave

/ f 0 ave

I av

e / I0 a

ve

SMBICJI

Duan X. R. 2013, NF53, 104009


HL-2AL-I-H transition by sawtooth crashes

• L-H transition may be

triggered by sawtooth crashes

• Plasma density and energy

increase with time

• The frequency of I-phase

oscillations decrease from

2.2kHz, 1.9kHz to 1.4 kHz.

• The I-H transition

successfully after the fourth

sawtooth crash

600 620 640 660 680 700 720 740 760

0.1

0.2

0.3

0.4

Time (ms)

I-D

,d

iv (

a.u

.)

0

0.2

0.4

0.6

0.8

1

1.2

I-s

x (

a.u

.)

1.5

2

2.5

3

0.82

0.30

0.80

0.67

0.18

0.50

0.60

0.74

L-mode

(b)

2.2 kHz 1.9 kHz 1.4 kHz

(c)I-phase

WE (10 kJ)

ne(1019 m-3)

type-III ELMs type-III ELMyH-mode

0.40(a) # 19720

Liu C. H. et al. EPS2013, P5.157

Zhao K. J. et al. NF 53 (2013) 123015


HL-2AELM-free H-mode with EHO-like

• EHO-like mode leads to density rate dropping and turbulent particle flux rising in SOL

• This mode located near

r/a=0.94) with f=5-10

kHz and mode number

m/n=3/1

• The EHO appears on D

and SXR emission

Zhong W. L. 2013, NF53, 083030


HL-2AStrong particle convection after SMBI

Yu D. L. 2012, NF 52, 082001

• The density at outer channels (Z = -17.5, 24.5 cm) drop after a few milliseconds fuelled by SMBI

• The density at central region (Z = ±3.5 cm) sustains about 30 ms to be dropping

• The density gradually peaks after SMBI (h).

• The results indicate that strongly inward convection exists after SMBI


HL-2AImpurity transport in Ohmic and ECRH

0

0.2

0.4

0.6

0.8

1.0

1.2

0

2

4

6

8

0 10 20 30 40 50

CV

(10

-6W

cm-2

)

CIV

(10

-5W

cm-2

)

V=-1m/s

CIVCV(a) Ohmic

r (cm)

0

1

2

3

0

1

2

3

4

0 10 20 30 40 50

CV

(10

-6W

cm-2

)

CIV

(10

-4W

cm-2

)

r (cm)

V=7m/s

V=-1m/s

CIV

CV

ECRH

• There is a good agreement between the simulation (lines) and the experiments (symbols) results with diffusion D = 0.6 m2/s and inner convection V(a) = -1 m/s in Ohmic plasma

• The strong decrease of the CV intensity compared with CIV in ECRH can only be reproduced with outer convection V(a) = 7 m/s

(b)

Cui Z. Y. et al 2013, NF 53, 093001


HL-2A

HL-2A tokamak





Summary

Outline


HL-2ABasis of Energetic Physics

• Beta-induced Alfven eigenmode (e-BAE) by energetic electrons was identified for the first time

• Multiple BAE modes are investigated• Ion and electron fishbones were

confirmed• The frequency jump of e-fishbone

was found uring ECRH. • Long-lived runaway electron beam

was observed during major disruptions (Zhang Y.P., PoP 19 (2012) 032510)

• The fast ion slowing-down time is in agreement with classical theoretical prediction (Zhang Y.P., PoP 19 (2012) 112504)

time (ms)

f (kH

z)

200 400 600 800 1000 12000

10

20

30

-0.50 0.5

0.5

1

e-BAE

ECRH

Mir (a.u) NBI

m-BAE

a（）

b（）

c（）

ne (1019 m-3)

TMnoise

Chen W., NF 49 (2009) 075022Chen W., NF 50 (2010) 084008Chen W., PRL 105 (2010)18500Chen W., NF 51 (2011) 063010


HL-2ABeta-induced Alfvén acoustic eigenmode

• BAAE with f = 15-40 kHz identified by frequency up-chirping, consistent with the solution for Alfvén-acoustic continuum

• A clear spectrum splitting is first observed on BAAE

Shot 10391

•Ip = 170 kA

•Bt = 1.4T,

•qa 4.0,

•Te 1.0 keV

•Ti 0.8 keV

•PNBI =0.6 MW

Alfvén-acoustic mode

Tearing mode

Splitting

Liu Yi, et al 2012, NF 52 074008


HL-2AFrequency jump of e-fishbone mode

Ip=155-160 kA

ne=0.3~0.7×1019m-3

BT=1.2-1.22 T

ECRH deposited

inside q=1 surface

• Both low and high frequency branches are observed• The high frequency branch could be observed only if

PECRH > 0.8 MW

• Frequency jump gap increases with the ECRH power • Low & high frequency modes are m/n = 1/1 and 2/2

Electron fishbone frequency jump was observed in the low density ECRH plasma, where the trapped particles are dominant.

Yu L. M., et al NF53, 053002


HL-2ALow-frequency multimode coexistance

• Low frequency multiple Alfven modes coexist during high power ECRH.

• Mode frequencies decrease with ne

and slightly increase with Te, finally

overlap with each other.

Ip= 155-160 kA Bt = 1.2-1.4 T

ne < 1.4 × 1013cm-3 PECRH > 0.6 MW

m/n = 4/2, 5/2, 3/1, 6/2, 4/1

Ding X. T. et al 2013 NF 53 043015


HL-2ALong lived mode & its control

LLM suppressed by ECRH or SMBILLM observed during NBI with weakly reversed or broad low magnetic shear

• LLM degrades plasma confinement and enhances fast ion loss

• LLM oscillation in LFS is stronger than that in HFS

Deng W. et al. 2014, NF 54 013010


HL-2A

HL-2A tokamak





Summary

Outline


HL-2ABasis of edge turbulence and ZFs

• The toroidal symmetries of GAM

and LFZF were confirmed on HL-

2A for the first time

• Turbulence nonlinear energy

transfer was identified for the first

time

• Two types of LCO were founded

• Three dimensional structure of

filamentary plasma was studied

•Zhao K.J., PRL 96 (2006) 255004

•Yan L.W., NF 47 (2007) 1673

•Zhao K.J., PoP 14 (2007)122301

•Lan T., PoP 15 (2008) 056105

•Zhao K.J., NF 49 (2009) 085027

•Cheng J., NF 49 (2009) 085030

•Liu A.D., PRL103 (2009) 095002

•Zhao K.J., PPCF 52 (2010)1240081 10 100

0

2

4

6

8

pow

er(a

,u)

f(kHz)

1 10 1000

1

2

3

pow

er(a

,u)

(a)

(b)

GAM

q=6.2

q=5.2

q=3.5

380kW

680kw

GAM

LFZF

LFZF


HL-2ANonlinear energy transfer

• Turbulent kinetic energy was transferred into LFZFs and GAMs

• the energy transferred into LFZFs increases with heating power

• Turbulence drives low frequency sheared flows

1 1

1

*( ) Rev f f f ff

T f v v v

Nonlinear energy transfer rate

Xu M. et al. 2012 PRL 108, 245001


HL-2ATwo types of I-phase trajectory

• Trajectories of the system in phase space of normalized radial electric field Er and RMS of the density envelope (20-100 kHz) measured at Δr =

−5 mm for discharge with L-I-H transition (a) and L-I-L transition (b).

Cheng J. et al. 2013 PRL. 110 265002


HL-2A

• Eddy amplitude increases firstly, it is stretched and split into two islands by strong E×B flow, finally plasma filaments are ejected into SOL

• The flow shearing time at filamentary birth position is identified to be close to the filament generation time (~4 s )

r (mm)

( s

)

-10 -5 0 5 10 15

-8

-6

-4

-2

0

2

-0.50.51.52.5

0.1

0.2

0.3

I s (A

)

-40 -20 0 20 40

0

1

2

3

(s)

Rs' (

108 m

s-2)

(c)(a)

(b) = -4 s

E (10

5s

-1)

Filament generation near the inner LCFS

-10 0 100

10

20

30

-10 0 100

10

20

30

r (mm)

Polo

idal

(m

m)

-10 0 100

10

20

30

r (mm)-10 0 10

0

10

20

30

r (mm)-10 0 10

0

10

20

30

Polo

idal

(m

m)

-10 0 100

10

20

30 (a) (b) (c)

(d) (e) (f)

-8s -6s -4s

-2s 0s 2s

Ip = 160-170 kA

Bt =1.8-1.9 T

ne= 1.8-2.5×1013cm-3

q95= 4.5-5.5

r/a = 0.96-1

Dependent on the significant parallel correlation

Spatiotemporal evolution of E×B shearing rate

trE )/Br/E(

Cheng J. et al 2013 NF53, 093008


HL-2ASummary• MSE, FILD, and MWR with high resolutions succeeded• ELM frequency rises to a factor of 2-3.5 but its amplitude drops

38% by using SMBI/CJI mitigation.• CJI is more efficient than SMBI for the ELM mitigation• L-I-H transition can be induced by sawtooth crashes• ELM-free H-mode observed with m/n=3/1 EHO mode of 5-8 kHz• The SMBI fuelling efficiency is enhanced by strong convection• The strong decrease of the CV intensity compared with CIV in

ECRH needs a outer convection velocity of 7 m/s• Frequency jump of e-fishbone and LF multimode coexistence• Long lived modes have been controlled by ECRH and SMBI• Turbulent energy transferred into ZFs ＆ GAM by nonlinear

process• Normalized Er ~ 1 is critical to trigger L-I-H transition• Plasma filament just generated at the inner LCFS


HL-2A

Thank you for your attention !

Southwestern Institute of Physics, Chengdu, China

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