Adanced Interferometry Techniques for Burning Plasmas Brower D L, Ding W X, Mirnov V V, et al. Advanced Interferometry Techniques for Burning Plasmas[C]//AIP Conference Proceedings. 2008, 988(1): 92. 组员: 顾翔 陶军 金钊 吴铭钐　胡文慧 彭浩 等离子体所 报告人：顾翔

For future burning plasma experiments, all diagnostics must be re-evaluated in terms of their measurement capabilities and robustness to the new environment This paper will explore a variety of phase measurement techniques for the main body and divertor regions that can be utilized on burning plasma experiments like ITER and beyond.

The scope of this work We will focus on a variety of phase measurement techniques： Conventionnal interferometry Faraday rotation Cotton-Mouton effect Fizeau interferometry 我们主要讨论几种相位测量技术：传统的干涉法；法拉第旋转；科顿-穆顿效应(Cotton-Mouton Effect) 又称磁双折射效应； 斐索干涉法

Conventionnal interferometry 基本原理示意图：

Conventionnal interferometry The resulting phase measurement can then be related to the plasma density according to the relation: 𝜙   Three assumptions: Magnetic field can be ignored The plasma is stationary Temperature effects are unimportant

Conventionnal interferometry If path length changes do occur, an extra phase term will be included. And if this term is large ,additional information is required to resolve the plasma density. An extra phase term: One way is adding an additional probe beam with spatial offset This approach is commonly referred to as 2-color interferometry (双色干涉仪).    

Conventionnal interferometry We will get these:   2 equations 2 unknowns If the two laser wavelengths are far apart, these can be written as:  

Conventionnal interferometry Drawback: fringe skip errors （条纹跳跃误差） Dispersion interferometer Two ways Differential interferometer

Conventionnal interferometry   相位差： V. P. Drachev, Yu. I. Krasnikovand P. A. Bagryansky Dispersion interferometer for controlled fusion devices Rev. Sci. Instrum. 64, 1010 (1993)

Conventionnal interferometry Differential interferometer（微分干涉仪）: Conventional interferometer phase shift induced by plasma, in a cylindrical geometry :   After Abel inversion(阿贝尔反演):   Ding W X, Brower D L, Deng B H, et al. Electron density measurement by differential interferometry[J]. Review of scientific instruments, 2006, 77(10): 10F105.

Conventionnal interferometry Differential interferometer（微分干涉仪）:

Faraday Rotation In physics, the Faraday effect or Faraday rotation is a magneto-optical phenomenon, that is, an interaction between light and a magnetic field in a medium. http://en.wikipedia.org/wiki/Faraday_effect

Faraday Rotation This measurement is immune to fringe counting errors The results can be expressed as the phase difference between R-wave and L-wave  

Faraday Rotation    

Faraday Rotation  

Cotton-Mouton Effect (科顿-穆顿效应) In physical optics, the Cotton–Mouton effect refers to birefringence in a liquid in the presence of a constant transverse magnetic field 和法拉第旋转一样不受条纹计数误差的影响； http://en.wikipedia.org/wiki/Cotton%E2%80%93Mouton_effect http://baike.baidu.com/view/675966.htm?fr=aladdin

Cotton-Mouton Effect The results can be expressed as the phase difference in the O-wave and X-wave  

Cotton-Mouton Effect

Fizeau Interferometer (菲佐干涉仪) Fizeau effect: the fizeau effect is the relativistic phase shift of an electromagnetic wave associated with movement of a dielectric medium. In the moving electron fluid, the phase shift experienced by an electromagnetic wave including Fizeau effect is  

Fizeau Interferometer Multiplying the Fizeau phase shift by the electron charge provides a line-integrated measure of the toroidal electron current density.

Finite Temperature Effects (有限温度效应) All interferometer and polarimeter phase shifts discussed to this point are based on cold plasma dispersion relation(i.e )     Finite temperature effects the electron plasma frequency increase decrease Relativistic effects The measured phase Mirnov :The conbined effect for ITER

Finite Temperature Effects   Phase correction factors   Measured phase shifts:    

Finite Temperature Effects

Fluctuation Measurements (波动测量) It is possible to make measurement with both high phase resolution and high time response