recent progress in mhd studies on hl-2a tokamak and future plans

SWIP 22/9/ 2007 Liu Yi

HL-2AHL-2A

Recent Progress in MHD studies on HL-2A tokamak and Future plans

Yi Liu, Y.B.Dong, W. Deng, J.Zhou, X.T.Ding

Southwestern Institute of Physics, Chengdu 610041, Chinae-mail contact of main author:[email protected]


HL-2AHL-2A

Experimental results on MHD activities

Identification and analysis of magnetic structures

Sawtooth features during ECRH (humpback, hill,..)

Control of sawtooth period (Stabilization and destabilization)

Exiting of the e-fishbone during ECRH

Disruption pridiction and mitigation

Future plan in MHD studies on HL-2A

Outline

1


HL-2AHL-2A

The mission of HL-2A include: – Improve the hardware

– Realize good plasma performance

– Explore physics issues

Main parameters of HL-2A•Major radius: 1.65 m•Minor radius: 0.40 m•Toroidal field: 2.8T•Plasma current: 480 kA•Magnetic flux: 5.0 Vs•Discharge duration:1.5 sec.•Plasma density: 6.0 x 1019 m-3

•Electron temperature:5.0k eV•Ion temperature: 600 eV

HL-2A tokamak

2

•ECRH system on HL-2A


HL-2AHL-2A HL-2A 装置放电控制及参数进展 Up to now, the stable and reproducible discharges with diver configuration

have been obtained, using the reliable feedback control.

Te=4930 eV

Discharge progress

The maximum temperature is 5keV

1.6MW ECRH heating ECRH

SMB injection(non-local effect, ITB formation)

Study on GEM Zonal Flow Study on MHD activities (e-fishbone, central relaxations, disruptions)


HL-2AHL-2A Techniques developed for MHD studies1

-1

r/a

r/a

-1 1

0

0.03667

0.07333

0.1100

0.1467

0.1833

0.2200

0.2567

0.2933

0.3300

0.3667

0.4033

0.4400

0.4767

0.5133

0.5500

q=1 surface

NO.1

NO.2

NO.5

NO.4

NO.3

The soft x ray camera on HL-2A

m=1 mode structure

Fast & Reliable Algorithms to construct images

for SX, HX ,Bolometer, HAlpha,…

Analytic algorithm (Series-expansion method)Constrained-optimization Method ((Pixel based) Hybrid MethodHopfield Neural Network

3

• Mirnov coils • 16 channel fast ECE• Soft X-ray camera • Hard X-ray camera


HL-2AHL-2A Improvement of Hybrid Method FEEDBACK TECHNIQUE

Since the Radon transform is linear

)( '' ffgg

)()()( ''' ffffgg

1/)(/1 2122 ii

ii FSn

Fitting accuracy

With Feedback(Y.Liu,Peterson)

Without Feedback(Y. Ohno)

Kyoto University

)])(())([( 11 fgfgEE T

4


HL-2AHL-2A

Tikhonov /Maximum entropy with GCV optimization

gm

data freconstruction with no use of gm

Prediction of fm by

mm Hgf

mf

GENERALIZED CROSS VALIDATION FOR OPTIMIZING

　 GCV()

ˆ 2

1 1M wi()

i1

M

Equation H f g

Tikhonov /Maximum regularization

P( f ) is a Penalty Function (Roughness of Image)

min .fP( f ) H f g 2

Final Prediction Error

Improvement to Regularization method

5


HL-2AHL-2A Identification and analysis of magnetic structures

28 Mirnov coils for MHD instability studies (m≤17, n≤4 )

Analysis of magnetic structures by modeling

HFS

R

LFS

6

18 pick-up coils

m=3 island

2

0 21

rj r j

a

0, cosj R Z j m n t

0 ,

1 1, ,R R z z surR z j R z

R R

Current filaments

• Z

(m)

•R (m)

•(a)

• Z (

m)

•R (m)

•(b)

Simulation the magnetic island IP=200~480kA, Bφ=2.0~2.8T


HL-2AHL-2A Analysis of magnetic structures

a b

c d

Z (

m)

Z (

m)

7

The structure of m=2 magnetic island Comparisons between inversion and measurement data, Shot03792.

• B ( T )* 1 0-

4

• B ( T )* 1 0-

4

•(a) •(b)

•(c) •(d)

220

1

k

i ii

B B

The least-square fitting to the poloidal Mirnov data to determine the parameters of perturbation currents, j0, and ∆Φ

Reconstruction of magnetic island


HL-2AHL-2A

Other topics including: Feature of steady m=1/n=1 phenomena triggered by MBI MHD mode activity and Sawtooth behaviour during ECH Features of sawtooth and m=1/n=1 mode after laser blow-off

MHD activities observed on HL-2A

A wide variety of MHD instabilities has been observed on the HL-2A tokamak.

Te0 or SXR

Auxiliary Heating

IP

Start-up Low sawtooth

Mirnov Large sawtooth,

Small disruption

Disruption

m=2 Fishbone

Plasma MHD Equilibrium(EFIT)

8


HL-2AHL-2A

m=1 mode and m=2 mode in a discharge after MBI and PI on the HL-2A .

m = 1 m = 29

Snake oscillation (m=1)


HL-2AHL-2A

The ideal MHD code MISHKA is capable to perform a computational normal-mode analysis for routine ideal MHD stability analysis of HL-2A

discharge.

Resistive Internal kink mode(m=1/n=1), instability responsible for sawteeth.

rad

ial d

isp

lace

me

nt

MISHKA: Ideal MHD Code

10

Simulation of MHD mode on HL-2A

Internal and external kink stability Extension to non-ideal MHD including– Drift– Neoclassical– Kinetic effects


HL-2AHL-2A

The m=2/ n=1 double tearing mode at the time of the reconnection

With resistivity , the equations for the perturbed quantities, u, T and b :

(o u),

o u (oT To) (Bo ) b (b) Bo ，

oT o u To (1)oTou (1)[2 Bo b]，

b (u Bo o b).

The CASTOR plasmas code computes the entire spectrum of normal-modes in resistive MHD for general tokamak configurations.

2 2.2 2.4 2.6 2.81

2

3

4

R ( m )2 2.2 2.4 2.6 2.8

-0.01

0

0.01

0.02

q

ξ

CASTOR: Resistive MHD Code

11


HL-2AHL-2A Feature of steady m=1/n=1 Phenomena Triggered by MBI

12

Effective refuelling

• Strong influence on MHD properties

10ms

20ms

MBI pulse

10ms

20ms

MBI pulse

Arrangement for MBI in the HL-2AGas pressure: 1 M Pa to 3 M PaPulse duration of Jet : 2 msPulse interval: 50 ms to 100 ms

The plasma density increases after MBI, while a temperature drop was observed in the central ECE channel.

Stair-shaped density increments Multi-pulse MBI experiment

Observation of snake

Trigger of ITB during ECRH


HL-2AHL-2A

0.8

0.20

0.32

0.2

340 360

m=1 oscillation

Center channel

Outer channel

Isx (a.u.)

MBI

Isx (a.u.)

T (m s)

m=1 oscillation

First sawtooth crash

Crash phase

0

0.12000.24000.36000.48000.60000.72000.84000.96001.0801.200

1.4401.5601.6801.8001.9202.0402.1602.280

-1

-

1.680

0

0.2800

0.4200

0.5600

0.7000

0.8400

0.9800

1.120

1.260

1.400

1.820

1.960

2.100

2.240

2.380

2.520

2.660

2.800-1

10

0.13000.26000.39000.52000.65000.78000.91001.0401.1701.3001.4301.5601.6901.8201.9502.0802.2102.3402.4702.600

1

r/a

1

0

0.14000.28000.42000.56000.70000.84000.98001.1201.2601.4001.5401.6801.8201.9602.1002.2402.3802.5202.6602.800

-1

1

r/a

-1

1

-1

1

Snake-like events surviving a crash

Feature of steady m=1/n=1 Phenomena Triggered by MBI

Steady-state m/n=1/1 perturbation with a feature of hot core displacement. It indicates the jet may penetrate into the core region of the plasma, and cause the formation of a persistent m/n=1/1 oscillation jut as pellets

A large, persistent m/n=1/1 perturbation with a rotating frequency of 4kHz has newly been observed in the core region after injection of MBI .

This usually happens in the decay phase after a stair-shaped density increment.

The oscillations grew rapidly at the beginning, then saturated for a long time. It can survive the subsequent sawtooth crash.

13


HL-2AHL-2A

345 346 347 348

T(ms)

Ui

-1 .0 -0 .8 -0 .6 -0 .4 -0 .2 0 .0 0 .2 0 .4 0 .6 0 .8 1 .0

-0 .4-0 .20 .00 .20 .40 .6

r/a

-0 .6-0 .4-0 .20 .00 .20 .40 .60 .8

Vi

0 .0

0 .2

0 .4

0 .6

k=1

k=2

k=3

(a) (b)

345 346 347 348

T(ms)

Ui

-1 .0 -0 .8 -0 .6 -0 .4 -0 .2 0 .0 0 .2 0 .4 0 .6 0 .8 1 .0

-0 .4-0 .20 .00 .20 .40 .6

r/a

-0 .6-0 .4-0 .20 .00 .20 .40 .60 .8

Vi

0 .0

0 .2

0 .4

0 .6

k=1

k=2

k=3

(a) (b)

SVD analysis of signals: (a) time evolution of principal components; (b) spatial eigenfunctions.

Feature of steady m=1/n=1 Phenomena Triggered by MBI

The central q(r) profile may be nonmonotonic with qmin above but close to 1 because of the increased resistivity due to the sudden drop of temperature over the core region. Such a q profile may lead to a nonlinear saturated ideal m=1 displacement as:

the is the critical value

1)(

3

8

71

8 2/32''2

q

q

q

q c

cq

Possible explanation:

14


HL-2AHL-2A

Happened in low density range

（ ne~1-2x1013cm-3 ） Located between q=1 and q=2 surface

Central temperature increase of 200ev

high field side

A steep Te profile in the plasma core is sustained for about 40ms

Ha and radiation losses drop （ Enhanced energy confinement ）

ITB formed between q=1 and q=2 rational surface

q=2

Showing formation of an ITB

15


HL-2AHL-2A

ITB events after SMBI

ITB Triggered by MBI

( Bt = 2.31 T, ne = 1.0×1019 m-3, Ip = 250 kA,.)

ITB formation during ECRH

ITB formation during ECRH and OH.

(PECRH = 800 kW, TSMBI = 810 ms)

Improvement of global confinement

16


HL-2AHL-2A Features of sawtooth and m=1/n=1 mode after Laser blow-off

Impurities have been injected into ohmic hydrogen discharges by laser blow-off for transport studies. The influences of sawtooth activity on impurity transport are studied.

Time evolution of the plasma current, loop voltage and electron density, the Al line brightness from VUV ， the soft X-ray and bolometer signals.

The system of laser blow-off Parameters:30ns pulse length1053nm wavelength10J energy0.6-1.5x1013cm-3 background densityTitanium and aluminum 17


HL-2AHL-2A Features of sawtooth after Laser blow-off

Inverted sawtooth

A jump is clearly seen during the inverted sawtooth crash within 200us indicating a rapid inwards flux of impurity particles during the crash. The impurity transport is greatly enhanced during sawtooth crash: up to 10-15 times (inflow phase)in the range of 2-3 (decay phase) 0. 00E+00

2. 00E-014. 00E-016. 00E-018. 00E-011. 00E+001. 20E+001. 40E+001. 60E+001. 80E+002. 00E+00

-1. 1 -0. 6 -0. 1 0. 4 0. 9

816ms820ms

The impurity ion flux is strongly affected by the sawtooth activity exhibiting discontinuities at sawtooth crashes.

18


HL-2AHL-2A

• ECRH

–75GHz, 0.8 MW gyrotron power

– ~300ms pulse length

–Upgrade : 2.0 MW, 0.5s

• Lower Hybrid Current Drive

–2.4GHz, 1MW klystron power

–1.7 ≤ n// ≤ 2.3

–2005 upgrade: 2MW, 500ms

• NBI

-1MW(2007-2008)

LHCD

NBI

ECRH

HL-2A Heating and Current Drive

19


HL-2AHL-2A

Parameters of ECRH experiment

Sawtooth behaviour during ECH

A sawtooth tends to saturate or decrease in its ramp phase, and the sawtooth shape is usually changed, leading to formation of a saturated sawtooth, a compound sawtooth, a humpback or a hill.

The auxiliary heating power is up to 2MW in the ECRH experiment of HL-2A tokamak. on-axis ECH (with a more peaked profile)off-axis ECH (with flat profile, no “hot ears”)

normal

larger

smaller

double

saturated

giant

(a) on-axis ECH ( PECH=450kW);

(b) off-axis ECH (PECH=340kW)

20


HL-2AHL-2A

Non-standard sawtooth during ECRH

Double Sawtooth

Compound(saturated+double)Sawtooth

m=1 island

m=1island

SVD

SVD

21


HL-2AHL-2A

Central plasma relaxation oscillation during ECRH

22

•Heating effect during crash or reconnection


hills humpback

The Te growth in both case corresponds to some temporary improvement of the global confinement


HL-2AHL-2A

Delayed Te decrease

Off-axis ECRH Steep SX profile

Te increaseSimilar results observed on T-10 and TEXTOR(Nucl.Fusion 44,2004)

Reduced core transport after off-axis ECRH switch-off(1)

23


HL-2AHL-2A Reduced transport after ECRH switch-off(2)

Steep SX profile

Nearly unchanged Te0 Larger sawtooth

ne increase slightly

Off-axis ECRH switch-off leads to current density redistribution and transiently low shear, causing a local confinement improvement.


24


HL-2AHL-2A

Stabilization of sawtooth activity–giant sawtooth

Instability control by RF injection(1)

25

The most significant response to a change in the heating location is the rapid change in sawtooth shape and period as the heating location crosses the inversion surface.

A large increase in sawtooth period occurs when changing the

resonance location by just 1 cm(>1.3MW).

Large sawtooth


HL-2AHL-2A

Such effect of ECH are qualitatively validated by the HL-2A discharges.

The effect of localized ECRH on the local conductivity profile gives to variation in the current penetration time in the core

On-axis ECRH shortens the sawtooth period

Destabilization of sawtooth with ECRH A normal sawtooth becomes saturated with strong m=1 mode or becomes a compound sawtooth .

The current diffusion:

)(12

0bootj

rBrrt

s

The critical shear criterion: )(1 css On-axis ECRH leading to an increased '

Instability control by RF injection(2)

26


HL-2AHL-2A

By changing the heating location(on-axis or off-axis), the control of sawtooth period can be realized.

热岛结构

冷岛结构

Destabilization of sawtooth with ECRH

27


HL-2AHL-2A Exiting of the m=1/n=1 kink mode during ECRH

Electron fishbone excited by the barely trapped electronsThe experimental results of E-fishbone onHL-1M(Ding X.T,Liu Yi,Nuclear Fusion Vol.42,No5(2002)491)

Electron fishbone excited by the circulating electronsThe experimental results of E-fishbone onHL-2A(Z.T.Wang,Nuclear Fusion Vol.42,No5(2002)491)

28


HL-2AHL-2A

BT=2.36,T, PECRH = 650kW (800-1100ms), Ne = 2.2 x 1013 cm –13

Fishbone like instabilities

•0.4

•0.5

• f（kHz）

•wavelet spectrum

•700 •705 •710 •715 •720 •725 •730

•5

•15

•20

•10

• population of trapped fast particles drives central kink mode

• resonance between banana precession drift and mode rotation

• central kink mode ejects fast particles nonlinear cycles

Fast particle driven instabilities: Fishbones

Crash

29


HL-2AHL-2A

E-fishbone

SHOT 6061:BT=2.45T (off-axis heating)PECRH =150kW (800-1200ms)Ne = 2.9 x 1013 cm –13

During ECRH

Two kinds of mode: Tearing mode, E-fishbone mode

Tearing mode

Before ECRH

1. 5

1. 7

1. 9

2. 1

2. 3

2. 5

2. 7

1088. 5 1089 1089. 5 1090

49 channel9 channel52 channel12 channel

a

b

c

d Shot 6061

q =1

ab

cd

Soft x ray array

Soft x ray array

I sx（ a.u.）

30

Ion diamagnetic drift


HL-2AHL-2A

m=1/n=1 “fishbone like instaility” exited with

Electron density < 3x1013cm-3

Power of ECRH < 900kW

Both high field side and low field side deposition

E-fishbone disappeared when power >900kW

31

Low field side deposition PECRH =650kW

High field side deposition PECRH=280kW


HL-2AHL-2A

Vertical Energy of the Superthermal Trapped Electron versus Bounce angle

30 – 60 keV

10 –30 keV

90 105 120 135 150 165 1800

20

40

60

80

100

120

EV (

keV

)

b

s=-0.4 s=-0.2 s=-0.05 s=0.05 s=0.2 s=0.4

HL-2A

32

Destabilizing effect of suprathermal electrons

Increase of hard X ray during ECRH Electron fishbone excited by the barely trapped electrons(Procession reversal )(Ding X.T,Liu Yi,Nuclear Fusion Vol.42,No5(2002)491)

Electron fishbone excited by the circulating electrons

Z.T.Wang,Nuclear Fusion47

0.0 0.2 0.4 0.6 0.8 1.0

-0.4

-0.2

0.0

0.2

s=-0.1 s=-0.02 s=0 s=0.02 s=0.1

Gc

k

Normalized precession velocity of circulating electrons


HL-2AHL-2A

MHD instabilities as a trigger of internal transport barriers

Snake as a trigger of stationary large pressure gradient near q=1 surfaceFishbone as a trigger of periodical reduction of transport coefficientInternal transport barriers formed near a rational surface

MHD instabilities can also be beneficial

33


HL-2AHL-2A Snake as a trigger of RI-Mode

•Stationary large pressure gradient near q=1 surface

•(RI-Mode): confinement enhancement

RI-Mode L-Mode

34


HL-2AHL-2A

•A slight increase in core energy constant is observed, while the off-axis temperature decreases at the same time (hence increase),leading to the conclusion that the transport coefficients must be reduced.

•Possible explanation: a redistribution of the resonant fast particles

eT

ITB triggering by E-fishbone

E-fishbone

An electron transport barrier has been probably formed at the position just outside the q = 1 surface

35


HL-2AHL-2A Disruption Studies

热岛结构

冷岛结构

Disruption: density-,low-q limits, locked mode at low density

•fast disruption in 4-6ms •dIP/dt during current quench

•stable state

• disruption

•Features of disruption on HL-2A

•Warning signals

–MHD mode

–Mixture of mode

36


HL-2AHL-2A

Discharge trajectories, w/o disruption discharges on Hugill diagram.

Shot:03038

Shot:03039Shot:03037

Shot:03054

Disruption

Greenwald limit

0.5

0.0

0.0 4.0

1/q a

neR/BT

Evolutions of plasma radiation at disruption.

Disruption free discharges

395

-382

r,

mm

t, ms470 475

b,

a.u.

Plasma current

Disruption

(a)

Mirnov

t, ms

475

472

395

-382

r, mm

m = 1 kink-like radiation(b)

Density limit disruption

•A radiative collapse

Healing of plasma modes with additional heating (ECRH,NBI) is planned

37


HL-2AHL-2A

Evolution of Parameters during a density limit disruption.

The plasma current, impurity intensities, electron density, plasma radiations,

profiles of electron temperature, and the soft X ray emissions.

300

01.0

0.05.0

0.0

0340

-330

I P, k

Ar,

mm

n e, m

-3P

imp,

a.u.

Te(

t) ,

eV

t, ms440 485

×1019

Last sawtooth

8000.0

5.0

PR, a

.u. r =3cm r =-20cm r =-38cm

CIII, 97.7nm CIII, 464.7nm

Temporal evolution of the electron

temperature profile Te(r) during

disruption.

800

0

012 -41r, cm

Te(

r),

eV

t≤500ms

500ms~560ms

570ms~590ms

Evolution

38


HL-2AHL-2A

Prediction and mitigation of disruptions

A neural network has been developed to predict the occurrence of disruptions

Mitigation of disruptions by fast helium gas puffs/MBI injection

42


HL-2AHL-2A Artificial neural networks (ANN method )

ANN has a complex structure, including many neurons and layers, and Signals transmitted to the neural network through the input layer. By calculating, the output of Layer 1 has been got, and then, the output of Layer 1 became the input of Layer 2. This process can be repeated until a final output has been got.

•ANN are trained to forecast the plasma disruptions in HL-2A tokamak.39


HL-2AHL-2A ANN results

database13 experimental diagnostic signals:

Mirnov probes, bolometer,

H-alpha line intensity, VUV

SXR, line integrated density

•The optimized network architecture is obtained.

alarm

Disruption

35ms in advance

•In the future, we want to use more (Mirnov signals, soft X ray,ect.) and then, we can predict short discharges with ANN. And at last, we are trying to predict disruption on-line.

40


HL-2AHL-2A Mitigation of disruptions

•A relatively large amount of helium gas puffing

•A relatively large amount of helium gas puffing

41


HL-2AHL-2A

At present, the heating power is not enough to study NTMs

• this will change when we get NBI – then, studies can be done

Work on ECCD (de)-stabilisation of sawteeth will be straightforward

• maybe together with q-profile diagnostics (stabilisation mechanism)How different is disruption on HL-2A from the rest of the world

Work on ECCD stabilisation/mitigation of disruptions could be interesting

• can be done with present system

• either heat MARFE or stabilise tearing mode

Work on correlation between MHD activities and ITB emergence

(monotonic q-profiles or non-monotonic q-profiles , ITBs linked with q=2 or q=3 radius)

Continue work on E-fishbone, its characteristic and its influence on the formation of ITB (with q-profile measurement or calculation, reflectometry for trbulence)

Proposals – Stability area

42


HL-2AHL-2A High Power Auxiliary Heating

To realize the physics objective of the HL-2A tokamak, the high power auxiliary heating systems will be established.

Profile control

Ip ( r ), P ( r )

NTM Control

ITB Control

NBI 1MW

ECRH/CD 2MW

LHCD 1MW

MSECXRSECE imaging

Re-establish H-mode in HL-2A Study on ELM mode

Study ITBs – also helps to get good performance

• electron cyclotron heating on the current ramp• electron ITB formation with MBI and ECRH• electron ITB should be possible with central ctr-ECCDMore ambitious: study fluctuations and transport

Study on correlation between MHD activities and ITB emergence

43


HL-2AHL-2A Control of NTM by ECCD

NTM control is a key issue for achieving steady state high βN

ECCD system

Steerable mirror with

wide steering range

•1-2MW•Modulated and non-modulated CD

ECCD

Steering mirror

Schematic of Current driving on resonant surface

• F a s t E C E & S X R a r e u s e d f o r e a r l y d e t e c t i o n o f i s l a n d

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

X A x i s T i t l e

Y A

xis

Titl

e

00 . 0 1 4 5 60 . 0 2 9 1 30 . 0 4 3 6 90 . 0 5 8 2 50 . 0 7 2 8 10 . 0 8 7 3 80 . 1 0 1 90 . 1 1 6 50 . 1 3 1 10 . 1 4 5 60 . 1 6 0 20 . 1 7 4 80 . 1 8 9 30 . 2 0 3 90 . 2 1 8 40 . 2 3 3 0

8 9 1 . 2 0 m s

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

X A x i s T i t l e

Y A

xis

Titl

e

00 . 0 1 3 7 50 . 0 2 7 5 00 . 0 4 1 2 50 . 0 5 5 0 00 . 0 6 8 7 50 . 0 8 2 5 00 . 0 9 6 2 50 . 1 1 0 00 . 1 2 3 80 . 1 3 7 50 . 1 5 1 30 . 1 6 5 00 . 1 7 8 80 . 1 9 2 50 . 2 0 6 30 . 2 2 0 0

8 9 1 . 2 3 5 m s

• F a s t E C E & S X R a r e u s e d f o r e a r l y d e t e c t i o n o f i s l a n d

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

X A x i s T i t l e

Y A

xis

Titl

e

00 . 0 1 4 5 60 . 0 2 9 1 30 . 0 4 3 6 90 . 0 5 8 2 50 . 0 7 2 8 10 . 0 8 7 3 80 . 1 0 1 90 . 1 1 6 50 . 1 3 1 10 . 1 4 5 60 . 1 6 0 20 . 1 7 4 80 . 1 8 9 30 . 2 0 3 90 . 2 1 8 40 . 2 3 3 0

8 9 1 . 2 0 m s

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

X A x i s T i t l e

Y A

xis

Titl

e

00 . 0 1 3 7 50 . 0 2 7 5 00 . 0 4 1 2 50 . 0 5 5 0 00 . 0 6 8 7 50 . 0 8 2 5 00 . 0 9 6 2 50 . 1 1 0 00 . 1 2 3 80 . 1 3 7 50 . 1 5 1 30 . 1 6 5 00 . 1 7 8 80 . 1 9 2 50 . 2 0 6 30 . 2 2 0 0

8 9 1 . 2 3 5 m s

44


HL-2AHL-2AInteraction between energetic electrons and waves

Charged fusion products transfer energy to electrons firstly, so the energetic electrons must be confined long enough without appreciable degradation due to collective modes and plasma turbulence.

Investigation of exciting condition of the electron fishbone:

E-fishbone with high power ECRH only;

E-fishbone with high power LHCD only;

The effect of PECRH/PLHCD;

The confinement of the energetic electrons.

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Investigation of exciting condition of the electron fishbone:

E-fishbone with high power ECRH only;

E-fishbone with high power LHCD only;

The effect of PECRH/PLHCD;

The confinement of the energetic electrons.

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Diagnostics

To investigate the 2-D velocity distribution of the energetic electrons:

Hard x ray imagingAnalysis of the ECE non-thermal spectra

To observe the direction of the wave excited by the energetic electrons

ECE imaging Soft x ray arrays in toroidal direction

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HL-2AHL-2A

Future plan in MHD studies on HL-2A

ELM and its control (Plasma shaping & ECRH)

MHD activity and formation of the ITB

MHD activity and formation of the ITB

Control of NTM mode

Control of sawtooth period

Control of sawtooth period

Development of ELM/RWM/EF control coils

Exiting of the e-fishbone during ECRH

Disruption mitigation and healing

Future plans

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HL-2AHL-2A

Thank you for your attention!

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recent progress in mhd studies on hl-2a tokamak and future plans

Documents