Measurement of magnetic island width by using multi-channel ECE radiometer on

HT-7 tokamak

Han Xiang(韩翔 ), Ling Bili(凌必利 ), Gao Xiang(高翔 ), Liu Yong(刘永 ), Ti Ang (提昂 ), Wang Yumin(王嵎民 )

July 19 2011

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Outline• Method to evaluate the magnetic island width by

ECE• specifications of HT-7 tokamak and multi-channel

ECE heterodyne radiometer• Measurement of magnetic island of electron

temperature on HT-7• Summary of this work

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• Method to evaluate the magnetic island width by ECE

• specifications of HT-7 tokamak and multi-channel ECE heterodyne radiometer

• Measurement of magnetic island from ECE on HT-7• Summary of this work

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Introduction

• The magnetic island can degrade the plasma confinement or even lead to a disruption• Such kind of destabilization is thought to be caused by the local loss of bootstrap current• It’s key issues that the magnetic island suppression for experimental tokamak or commercial reactors such as ITER• Electron cyclotron emission (ECE) as an primary diagnostic could be applied for magnetic island research

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A. Isayama et al. plasma phys. Control fusion 41 (1999) 35-43

ECE measurement on JT-60U

•Te profile for island width and its evolution•ECE oscillation contour for island width, rotation frequency, the inverted phase and so on

Inverted phase atR=3.65m

7widthR cm

e eT T

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2

2

1 t T

t Tf t f t f t dt

T

Nagayama et al. Phys. Plasmas 3, 7, 1996

ECE measurement on TFTR

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Nagayama et al. Phys. Plasmas 3, 7, 1996

Different island result on TFTR

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• Method to evaluate the magnetic island width by ECE

• specifications of HT-7 tokamak and multi-channel ECE heterodyne radiometer

• Measurement of magnetic island from ECE on HT-7• Summary of this work

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Major radius: R=1.22mMinor radius: a=0.27mLimiter: Mo & liquid LiHeating: Lower hybrid wave and ICRF

1.5 2.2

100 250T

P

B T

I kA

HT-7 tokamak

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•Horizontal distribution along middle plane•Spatial resolution: 2cm•2nd harmonic frequency: 98.5~126GHz•Channel location with frequency： 0 0 1eB R

Rm f

( / ) 1/n ce en n eB m B R 2

3 2( )

8 eI Tc

Multi-channel ECE on HT-7 tokamak

Heterodyne radiometer ECE diagnostic 10/18

• Method to evaluate the magnetic island width by ECE

• specifications of HT-7 tokamak and multi-channel ECE heterodyne radiometer

• Measurement of magnetic island from ECE on HT-7• Summary of this work

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ECE oscillation phase inverse

Mirnov coils oscillation

signals for shot 112810

19 3

100

1.75

2.4 10

p

t

e

I kA

B T

n cm

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ECE oscillation analysis for shot112810

frequency(GHz)

ECE0198.501

ECE02100.433

ECE03102.366

ECE04104.299

ECE05106.232

ECE06108.165

ECE08112.031

ECE10114

Location (m)

1.2171 1.1937 1.1711 1.1494 1.1285 1.1083 1.0701 1.0516

• oscillation phase inverse

0.06w m

1.12R m

• oscillation frequency: 3.5kHz• amplitude ~ 10%

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poloidal ： 12 coils, fixed among 30° measuring the poloidal mode

toroidal ： 9 coils, asymmetrical measuring the toroidal mode

Mirnov coils signals for Shot112810

m=2

n=1

4.2aq

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time: 515.066 0.02ms time: 536.617 0.02ms

5w cm4w cm

Two moments analysis for Shot112810

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• Method to evaluate the magnetic island width by ECE

• specifications of HT-7 tokamak and multi-channel ECE heterodyne radiometer

• Measurement of magnetic island from ECE on HT-7• Summary of this work

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The magnetic island width of m/n=2/1 mode is evaluated using ECE diagnostic on HT-7

Saturated island width of 2/1 mode is about 5cm,

; island rotation frequency is 3.5kHz.The island information can be obtained by ECE

diagnostic. This method is useful for the research of NTM on EAST experiment in the future.

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satw

0.16satw a

Thank you！

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