The ECEI Newest Experiment Results on HT-7

UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA

CAS KEY LABORATORY OF BASIC PLASMA PHYSICS

The ECEI Newest Experiment Results on HT-7

报告人：徐明2008-6-2

2008-6-2

Experiment Result of ECEI on HT-7 2


Outline Diagnostic Principles of ECEI Context knowledge

Introduction to Fluctuation of Te 2D imaging Introduction to Zonal flow

The experiment results on HT-7 2D imaging Te Fluctuations Zonal flow Muti magnetic island

Summarization



Diagnostic Principles of ECEI

2008-6-2



The development of ECEIECEI is the abbreviation of Electron Cyclotron Emission Imaging.

1974,ECE radiometry has been developed and used for a standard diagnostic for magnetic fusion plasmas.

1993, S. Sattler and H. J. Hartfuss applied the cross-correlation technology into the Te fluctuation measurement to estimate the radiation noise and improve the sensitivity of the ECE radiometer.

1995, G. Cima and C. Watts developed another cross-correlation technology along the sight line. The use of the cross-correlation techniques solves the problem of the radiation noise.

1997, ECEI has been developed and operated on the TEXT-U.

Subsequently, RTP, TEXTOR, LHD, DIII-D etc have equipped with ECEI.

2004,ECEI have applied on HT-7.

2008-6-2



)()()(])(

[2

2 Ij

N

I

ds

dN

rr

1

1

8,)1()(

23

3

TkBB BecIeII

1 eBTk2

23 )(8))((

Ic

RTe

ecen m

eBnn

R

RBB 00 Rm

ReBnn

ecen

00

Rn

1

)()( 2 RITe 一般只要合适的电子密度与温度就很容易满足

002 BTnR eeX

对于马克温度为 KeV的mm波辐射，条件满

足

The Physics Principle of ECEI

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2-D ECE Imaging (ECEI)

ECE measurement is an established tool for Te measurement in high temperature plasmas.

In conventional radiometry, a single antenna receives all frequencies. In ECEI, a vertically aligned antenna/mixer array employed as the receiver.

Contrasting, soft X imaging using the supposition of rotation rigid body, while ECEI can gain 2D imaging directly.

Unique advantages: High spatial and temporal resolution, 2-D correlation.

Conventional 1-D ECE System 2-D ECE Imaging System

2008-6-2



IFIFSYSTEMSYSTEM

ElectronicsElectronicsApparatusApparatus

Imaging System

Imaging Array

System of Data Acquisition

EC

EI

EC

EI

Array

Array

LO

Frequency 99-120GHz

window

IF signals3.2-6.8GHz

LabLab ViewView

LinuxLinux

IF signals

Electrical Signal

Plasma

The Constitution of ECEI

2008-6-2



Brief Introduction to the System of Intermediate Frequency

Mixers

Power Divider

Video Amps

Input Signal

Bandpass Filters

IF Amps

Microwave Amp

LO8LO7

LO6LO5LO4

LO3LO2

LO1

Detectors

T1

T2

T3

T4

T5

T6

T7

T8

Mixers

Power Divider

Video Amps

Input Signal

Bandpass Filters

IF Amps

Microwave Amp

LO8LO7

LO6LO5LO4

LO3LO2

LO1

Detectors

T1

T2

T3

T4

T5

T6

T7

T8

Brief introduction:The signal from antenna array to the System of Intermediate Frequency and by dividing the input signal into eight channels. The output signal from the T1 to T8 is display as: 3.2,3.8,4.3,4.8,5.3,5.8,6.3,

6.8GHz.

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The sample volume of ECEI The direction of poloidal

sample volume ~1.1cm Channel interval~1.3cm

The direction of radius sample length is narrow~5-6cm.

Diagnosis volume: 5.6cmx22.4cm(8x16 channels)

Time discrimination~4us

该系统噪信比量级 ~1%, 可实时研究>1%涨落 ,长时间积分研究 >0.1%涨落

The sample volume is lie on the height of window, the higher the window, the smaller of the sample volume.

The sample volume determine the magnification of lens system.

The channel interval is required bigger the sample volume and smaller the correlation length of turbulence.



Context knowledge

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The knowledge of the Te fluctuation in core of plasmas

欧姆定标律 :线性区和饱和区线性区由电子模主导 ,饱和区由离子模主导电子模在电子逆磁漂移方向 ,离子模在离子逆磁漂移方向 ,方向正好相反 TEXT-U利用 FIR,BES观测到过高密度下 ,密度涨落中存在离子模

2008-6-2



Sawtooth reconnection model of m=1

Full magnetic reconnection model Kadomtsev(’76) Declare the core q0 drop after t

he crash q0 keep~0.7(TEXTOR & TFT

R) q0 is 0.7 ~1.0 (DIIID)

The reconnection time of theory result is fast than that of experiment results

Quasi-interchange model (R.Granets(’88))

3D local reconnection model M.Yamada(’94) Y.Nagayama(’96)

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The experiment result of study m=1 mode

Results of soft X imaging sustain lots of models, sometimes self-contradictionReference:S.Yamaguchi(’04)

Results of 2-D imaging through by reconstruct 1-D ECE sustain model as follow:Ⅰfull reconnection model;Ⅱ3-D local reconnection modelExplain the asymmetry of ballooning

2008-6-2



2D ECE imaging2D imaging of ECEI on TEXTOR

Magnetic reconnection process of full magnetic reconnection model arises in the experiments, but the process merely be possibly appear a quarter of torus

Have same characteristic of ballooning model

2008-6-2



Brief Introduction to Zonal flow

Zonal flow of Jupiter

在环形磁约束等离子体中， ZF是本征模。但它是湍流驱动的，是线性稳定的，且不直接驱动径向输运。它与漂移波湍流一起，构成漂移波—带状流系统。

P. H. Diamond et al. PPCF 47, R35 (2005)

Zonal flows, by which we mean azimuthally symmetric band-like shear flows, are a ubiquitous phenomena in nature and the laboratory.



The Experiment Results of ECEI on HT-7

The Experiment and Relative Result all disposed by Xiaoyuan Xu

2008-6-2



The Relating Parameters of HT-7 The overall Parameters of HT-7 tokamak

R=122cm, a=27cm

The Parameters of Plasmas: Ip=170kA,Bt=1.9T,qa~3 The Radius of Surface q=1(~7cm)The Reconnection Time of Kadomtsev:

1~ ~1702k A R s

13 31.6 ~ 4.5 10 , (0) ~ 800 , ~ 0.3e pn cm Te eV

2008-6-2



Section plane of electron temperature

-15 -10 -5 0

0.2

0.25

0.3

0.35

0.4

0.45

0.5

r (cm)

Te (a

.u.)

eceecei

r (cm)

Z (c

m)

-20 -15 -10 -5 0 5-10

-8

-6

-4

-2

0

2

4

6

8

10

0.4

0.45

0.5

0.55

0.6

0.65

0.7

Radius calibration using scanning toroidal magnetic and the result in accord to the result of ECE.

Poloidal calibration through moving the equipment down and up and obtaining a perfect 2D Te section plane.

2008-6-2



0 50 100 150 200 2500

0.5

1

1.5

2

2.5

3

/2 (kHz)

k (cm

- 1)

Er = - 6kV/m

Er = 0

(b)

0 50 100 150 200 25010

-11

10-10

10-9

/2 (kHz)

statistical noise level

(a)

Electron mode of fluctuation of Te at low density

Cross-power spectrum and spectrumlocation:r/a=0.59Poloidal interval: 2.2cmFrequency discrimination: 7.8kHz

ExB drift: edw E B

Linear frequency of electron drift wave:

* 2 2[1/(1 )]k e sk *e e nk cT eBL 1/ 2( / )s i e iT T

Electron drift wave:Electron gyration diamagnetic

Wave vector: ~ 0.3sk

k

BEk rBE

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0 2 4 6 8 10 12 14

-85-80-75-70-65

H()(

dB

)

r=11.6,11.6cm =-31,31o (dr,d=-0.0,12.5cm)

0 2 4 6 8 10 12 14

0.20.40.60.8

Cohere

nt

0 2 4 6 8 10 12 14-1

0

1

Mode N

um

ber

/2 (kHz)

0 2 4 6 8 10 12 14

-90

-80

-70

H()(

dB

)

r=12.4,12.4cm =-37,37o (dr,d=-0.0,15.8cm)

0 2 4 6 8 10 12 14

0.20.40.60.8

Cohere

nt

0 2 4 6 8 10 12 14-1

0

1M

ode N

um

ber

/2 (kHz)

Poloidal interval is:12.5cm,15.8cm

For the increase of poloidal interval, the fluctuation coherence of big wave number is reduced and the trend of tend to zero is obvious.

The Experiment Result of Zonal flow——Poloidal(1)

Cross-power spectrum, coherence spectrum and number of mode

ne=1.6

poloidal wave number is perfect to be zero for frequency at 0-2kHz

2008-6-2



0 2 4 6 8 10 12 14

-90

-80

-70

H()(

dB

)

r=11.6,11.6cm =-31,31o (dr,d=-0.0,12.5cm)

0 2 4 6 8 10 12 14

0.2

0.4

0.6

Cohere

nt

0 2 4 6 8 10 12 14-1

0

1

Mode N

um

ber

/2 (kHz)

0 2 4 6 8 10 12 14

-90

-80

-70

H()(

dB

)

r=12.4,12.4cm =-37,37o (dr,d=-0.0,15.8cm)

0 2 4 6 8 10 12 14

0.20.40.6

Cohere

nt

0 2 4 6 8 10 12 14-1

0

1

Mode N

um

ber

/2 (kHz)

The Experiment Result of Zonal flow——Poloidal(2)

ne=3.3

When the electron density is great than 3.3, characteristic of low frequency fluctuation of poloidal wave number tend to be zero is unobvious.This phenomenon may be explain that the zonal flow is damped for the strength of ion collision frequency .

Poloidal interval is:12.5cm,15.8cm

Cross-power spectrum, coherence spectrum and number of mode

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( ~ 1.7)eon

0k

0rk

poloidal correlation

0k

0rk

2008-6-2



The Experiment Result of Zonal flow——toroidal

Toroidal correlationCross-power spectrum, coherence spectrum and number of mode.

As the increasing of density, the power spectrum, coherence and mode have characteristic of decrease.

Reasonable explain is that collision frequency of ion increasing, and result in the damp of zonal flow.

2008-6-2



( ~ 1.7)eon

0k

0rk

toroidal correlation

0k

0rk

2008-6-2



Coexist of electron mode and ion mode at high density

TEXT-U has been utilized FIR&BES found the ion mode while measuring the fluctuation of density of high density.

At HT-7 we using ECEI measure the fluctuation of temperature and found the coexist of electron mode and ion mode in the high density of 4.5, and also found this phenomenon exist on low field side and high field side.

2008-6-2



2D evolution of Te fluctuation ——low field side

Parameter: Ip=170kA ne=2.3 qa=3.3

2000 2500 3000-0.06-0.04-0.02

00.020.04

2660 2680 2700 2720 2740 2760 2780 2800 2820 2840-0.1

0

0.1

t (s) T

e/Te

1 23 4 56 7 8

1

r (cm)

Z (cm

)

8 10-10

-5

0

5

10

2

r (cm)8 10

-10

-5

0

5

10

3

r (cm)8 10

-10

-5

0

5

104

r (cm)8 10

-10

-5

0

5

10

5

r (cm)8 10

-10

-5

0

5

10

6

r (cm)8 10

-10

-5

0

5

107

r (cm)8 10

-10

-5

0

5

10

8

r (cm)

8 10-10

-5

0

5

10

-0.1

-0.05

0

0.05

0.1

Kink instability emerged and developing

Forms an ‘‘X point’’ in the poloidal plane leads to the reconnection

heat is accumulated outside the inversion radius and crashed the end

2008-6-2



2D evolution of Te fluctuation ——high field side

Parameters: Ip=160kA ne=1.9x1019m-3

qa=3.2

Before the crash, it appear weak magnetic reconnection

At the end of broken up, their appeared evidence of heat starts to flow to the outside through a small opening.

140016001800200022002400-0.05

0

0.05

2000 2100 2200 2300 2400-0.1

0

0.1

t (s)

Te/

Te

1 2 34567 8

1

r (cm)

Z (cm

)

-8 -6-10

-5

0

5

10

2

r (cm)-8 -6

-10

-5

0

5

10

3

r (cm)-8 -6

-10

-5

0

5

104

r (cm)-8 -6

-10

-5

0

5

10

5

r (cm)-8 -6

-10

-5

0

5

10

6

r (cm)-8 -6

-10

-5

0

5

107

r (cm)-8 -6

-10

-5

0

5

10

8

r (cm)

-8 -6-10

-5

0

5

10

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

2008-6-2



Muti Magnetic Island-(Ⅰ)

2000 2500 3000-0.05

00.05

2650 2700 2750 2800 2850 2900 2950 3000 3050-0.1

0

0.1

t (s) T

e/Te

1 2 345 6 7 8

1

r (cm)

Z (cm

)

8 10-10

-5

0

5

10

2

r (cm)8 10

-10

-5

0

5

10

3

r (cm)8 10

-10

-5

0

5

104

r (cm)8 10

-10

-5

0

5

10

5

r (cm)8 10

-10

-5

0

5

10

6

r (cm)8 10

-10

-5

0

5

107

r (cm)8 10

-10

-5

0

5

10

8

r (cm)

8 10-10

-5

0

5

10

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

The process evolvement of Dual Magnetic Island and crash up in the end.

Muti Magnetic Island in the surface of q=1 can only be trigged by mode of1/1,2/2,3/3,..

2008-6-2



Muti Magnetic Island-(Ⅱ)

The evidence of 1/1,2/2,3/3 mode exist in the surface of q=1

5kHz, 10kHz, 15.5kHz

0 5 10 15 20 25

-85-80-75-70-65

H(

)(dB

)

0 5 10 15 20 250

0.5

1

Cohere

nt

0 5 10 15 20 250123

mode n

um

/2 (kHz) #102843_5-9,5-7

0 5 10 15 20 25-100

-80

H()(

dB

)

0 5 10 15 20 250

0.5

1C

ohere

nt

0 5 10 15 20 250123

mode n

um

/2 (kHz) #102843_2-1,6-7

2 / /m r k m r

2008-6-2



Muti Magnetic Island-(Ⅲ) bicoherence spectrum Frequency discrimination:

0.78kHz have action of each other

the mode of 1/1,2/2,3/3

0 5 10 15 20 25 30 35 40 45 500

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

f (kHz)

b

2 (f)

#102843_4-6

2008-6-2



Summarization It have found the evidence of zonal flow from st

udying the fluctuation of electron temperature in the plasmas core

We found the coexist of electron modes and ion modes in the fluctuation of electron temperature.

The low field side and the high field side do exist the phenomenon of magnetic reconnection, so we can exclude the quasi-interchange model.

At the q=1 surface exist the modes of 1/1,2/2,3/3,..., and these modes caused the phenomenon of multi magnetic island.



Thank you!

The ECEI Newest Experiment Results on HT-7

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