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The ECEI Newest Experiment Results on HT-7

The ECEI Newest Experiment Results on HT-7. 报告人：徐明 2008-6-2. 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

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The ECEI Newest Experiment Results on HT-7

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  1. The ECEI Newest Experiment Results on HT-7 报告人：徐明 2008-6-2

  2. Experiment Result of ECEI on HT-7 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 • TeFluctuations • Zonal flow • Muti magnetic island • Summarization

  3. Diagnostic Principles of ECEI

  4. Experiment Result of ECEI on HT-7 The development of ECEI ECEI 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.

  5. Experiment Result of ECEI on HT-7 The Physics Principle of ECEI 一般只要合适的电子密度与温度就很容易满足 对于马克温度为KeV的mm波辐射，条件满足

  6. Experiment Result of ECEI on HT-7 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

  7. LO Experiment Result of ECEI on HT-7 The Constitution of ECEI IF signals3.2-6.8GHz Imaging System Frequency 99-120GHz IF SYSTEM ECEI Array IF signals Imaging Array window Plasma Lab View Electronics Apparatus System of Data Acquisition Linux Electrical Signal

  8. Experiment Result of ECEI on HT-7 Brief Introduction to the System of Intermediate Frequency 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.

  9. The sample volume of ECEI Experiment Result of ECEI on HT-7 The sample volume is lie on the height of window, the higher the window, the smaller of the sample volume. The channel interval is required bigger the sample volume and smaller the correlation length of turbulence. The sample volume determine the magnification of lens system. 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 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

  10. Context knowledge

  11. Experiment Result of ECEI on HT-7 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

  12. Sawtooth reconnection model of m=1 Experiment Result of ECEI on HT-7 • Full magnetic reconnection model Kadomtsev(’76) • Declare the core q0 drop after the crash • q0 keep~0.7(TEXTOR & TFTR) • 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)

  13. The experiment result of study m=1 mode Experiment Result of ECEI on HT-7 Results of soft X imaging sustain lots of models, sometimes self-contradiction Reference: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 model Explain the asymmetry of ballooning

  14. Experiment Result of ECEI on HT-7 2D ECE imaging 2D 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

  15. Experiment Result of ECEI on HT-7 Brief Introduction to Zonal flow Zonal flows, by which we mean azimuthally symmetric band-like shear flows, are a ubiquitous phenomena in nature and the laboratory. 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)

  16. The Experiment Results of ECEI on HT-7 The Experiment and Relative Result all disposed by Xiaoyuan Xu

  17. The Relating Parameters of HT-7 Experiment Result of ECEI on 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:

  18. Section plane of electron temperature 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. Experiment Result of ECEI on HT-7

  19. ExB drift: Experiment Result of ECEI on HT-7 Electron mode of fluctuation of Te at low density Electron gyrationdiamagnetic Electron drift wave: Wave vector: Linear frequency of electron drift wave: • Cross-power spectrum and • spectrum • location:r/a=0.59 • Poloidal interval: 2.2cm • Frequency discrimination: 7.8kHz

  20. Experiment Result of ECEI on HT-7 ne=1.6 The Experiment Result of Zonal flow——Poloidal(1) Cross-power spectrum, coherence spectrum and number of mode Poloidal interval is:12.5cm,15.8cm poloidal wave number is perfect to be zero for frequency at 0-2kHz For the increase of poloidal interval, the fluctuation coherence of big wave number is reduced and the trend of tend to zero is obvious.

  21. Experiment Result of ECEI on HT-7 ne=3.3 The Experiment Result of Zonal flow——Poloidal(2) Cross-power spectrum, coherence spectrum and number of mode Poloidal interval is:12.5cm,15.8cm 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 .

  22. Experiment Result of ECEI on HT-7 poloidal correlation

  23. Experiment Result of ECEI on HT-7 The Experiment Result of Zonal flow——toroidal Toroidal correlation Cross-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.

  24. Experiment Result of ECEI on HT-7 toroidal correlation

  25. Experiment Result of ECEI on HT-7 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.

  26. Experiment Result of ECEI on HT-7 2D evolution of Te fluctuation ——low field side Parameter: • Ip=170kA • ne=2.3 • qa=3.3 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

  27. Experiment Result of ECEI on HT-7 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.

  28. Experiment Result of ECEI on HT-7 Muti Magnetic Island-(Ⅰ) 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,..

  29. Experiment Result of ECEI on HT-7 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

  30. Experiment Result of ECEI on HT-7 Muti Magnetic Island-(Ⅲ) • bicoherence spectrum • Frequency discrimination:0.78kHz • have action of each other the mode of 1/1,2/2,3/3

  31. Experiment Result of ECEI on HT-7 Summarization • It have found the evidence of zonal flow from studying 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.

  32. Thank you!

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