微波多普勒反射计数据分析的一种优化方法

doi:10.16568/j.0254-6086.201901001

摘要/Abstract

摘要：

结合对多普勒频谱的分析，提出一种基于双高斯拟合的轴对称-非对称谱(SAS)分析方法。在此方法下，功率谱主要由轴对称功率谱和非轴对称功率谱两部分组成。前者主要由等离子体截止层密度的扰动调制决定，后者主要由波数为k _⊥=2k₀sinθ 的湍流的极向密度扰动决定。在分析多普勒反射计的数据时，相较于常用的频谱重心(COG)分析方法和相位微分(δ-phase)法，SAS 谱分析不仅提高了求取多普勒频移的准确性，同时还可以获取等离子体中波数为k_⊥ 的极向湍流的密度扰动强度和截止层的密度扰动强度。

关键词: 微波, 多普勒反射计, 对称-非对称谱数据处理, 等离子体旋转, 湍流

Abstract:

Combining with the analysis of Doppler spectrum, a new method, named symmetric-asymmetric spectrum (SAS) analysis is put forward based on dual Gauss fitting. A power spectrum is mainly composed of symmetric spectrum and asymmetric spectrum. The symmetric spectrum is principally decided by plasma cutoff density fluctuations, which can modulate the detecting signals, while the asymmetric spectrum is primarily determined by poloidal density fluctuations of k _⊥=2k₀sinθ turbulence. Compared with the commonly used method of spectral center of gravity (COG) and δ-phase method, SAS analysis not only improves the accuracy of the Doppler frequency shift measurements, but also provides the plasma density fluctuations of poloidal k_⊥ turbulence and cutoff.

Key words: Microwave Doppler reflectometer, SAS analysis, Plasma rotation, Turbulence

中图分类号:

TL65+2

闻杰，石中兵*，钟武律，梁桉树，蒋敏，施培万，杨曾辰，陈伟，方凯锐，刘泽田. 微波多普勒反射计数据分析的一种优化方法[J]. 核聚变与等离子体物理, 2019, 39(1): 1-8.

WEN Jie, SHI Zhong-bing, ZHONG Wu-lv, LIANG An-shu, JIANG Min, SHI Pei-wan, YANG Ceng-chen, CHEN Wei, FANG Kai-rui, LIU Ze-tian. Optimization for the data analysis of the microwave Doppler reflectometer[J]. NUCLEAR FUSION AND PLASMA PHYSICS, 2019, 39(1): 1-8.

参考文献

[1] Holzhauer E, Hirsch M, Grossmann T, et al. Theoretical and experimental investigation of the phase-runaway in microwave reflectometry [J]. Plasma Phys. Contr. Fusion,1998, 40(11): 1869.
[2] Hillesheim J C, Peebles W A, Rhodes T L, et al. A multichannel, frequency-modulated, tunable Doppler backscattering and reflectometry system [J]. Rev. Sci.Instrum., 2009, 80(8): 083507.
[3] Zou X L. Poloidal rotation measurement in Tore Supra by oblique reflectometry [R]. France: Proc. 4th International reflectometry workshop, 1999.
[4] Hirsch M, Holzhauer E, Baldzuhn J, et al. Doppler reflectometer for the investigation of propagating density perturbations [R]. France: Proc. 4th International reflectometry workshop, 1999.
[5] Shi Z B, Zhong W L, Jiang M, et al. A novel multi-channel quadrature Doppler backward scattering reflectometer on the HL-2A tokamak [J]. Rev. Sci.Instrum., 2016, 87(11): S780.
[6] Chen W, Xu Y, Ding X T, et al. Dynamics between the fishbone instability and nonlocal transient transport in HL-2A NBI plasmas [J]. Nucl. Fusion, 2016, 56(4):044001.
[7] Zhong W L, Shi Z B. Spatiotemporal characterization of zonal flows with multi-channel correlation Doppler reflectometers in the HL-2A tokamak [J]. Nucl. Fusion,2015, 55(11): 113005.
[8] Jiang M, Zhong W L, Xu Y, et al. Influence of m/n = 2/1 magnetic islands on perpendicular flows and turbulence in HL-2A ohmic plasmas [J]. Nucl. Fusion, 2018, 58(18):026002.
[9] Liang A S, Zhong W L, Zou X L, et al. Pedestal dynamics across low to high confinement regime in the HL-2A tokamak [J]. Phys. Plasmas, 2018, 25(2): 022501.
[10] Hennequin P, Honoré C, Truc A, et al. Fluctuation spectra and velocity profile from Doppler backscattering on Tore Supra [J]. Nucl. Fusion, 2006, 46(9): S771.
[11] Schirmer J, Conway G D, Zohm H, et al. The radial electric field and its associated shear in the ASDEX Upgrade tokamak [J]. Nucl. Fusion, 2006, 46(46): S780.
[12] Conway G D, Scott B, Schirmer J, et al. Direct measurement of zonal flows and geodesic acoustic mode oscillations in ASDEX upgrade using Doppler reflectometry [J]. Plasma Phys. Contr. Fusion, 2005, 47(8): 1165.
[13] Fanack C, Boucher I, Clairet F, et al. Ordinary-mode reflectometry: modification of the scattering and cut-off responses due to the shape of localized density fluctuations [J]. Plasma Phys. Contr. Fusion, 1996, 38(11): 1915.
[14] Boucher I, Fanack C, Heuraux S, et al. One-dimensional analytical model of the phase shift due to Bragg backscattering of an ordinary wave by large amplitude density fluctuations [J]. Plasma Phys. Contr. Fusion,1998, 40(40): 1489.
[15] Zhong W L, Shi Z B, Yang Z J, et al. Experimental observation of turbulence transition and a critical gradient threshold for trapped electron mode in tokamak plasmas [J]. Phys. Plasmas, 2016, 23(6): B557.
[16] 张博宇, 石中兵, 钟武律, 等. HL-2A 装置上的快扫Q波段微波反射系统研制 [J]. 核聚变与等离子体物理,2016, 36(4): 289-296.
[17] Laviron C, Donn A J H, Manso M E, et al. Reflectometry techniques for density profile measurements on fusion plasmas [J]. Plasma Phys. Contr. Fusion, 1996, 38(7):905-936.
[18] Hirsch M, Holzhauer E, Baldzuhn J, et al. Doppler reflectometry for the investigation of propagating density perturbations [J]. Plasma Phys. Contr. Fusion, 2001, 43(12): 1641-1660.
[19] Conway G D, Schirmer J, Klenge S, et al. Plasma rotation profile measurements using Doppler reflectometry [J]. Plasma Phys. Contr. Fusion, 2004, 46(6): 951.
[20] Tokuzawa T, Ejiri A, Kawahata K, et al. Microwave Doppler reflectometer system in LHD [J]. Rev. Sci.Instrum., 2012, 83(10): 813.
[21] Hirsch M, Holzhauer E, Baldzuhn J, et al. Doppler reflectometry for the investigation of propagating density perturbations [J]. Rev. Sci. Instrum., 2001, 72(1): 324-327.
[22] 钟武律. 基于先进微波诊断的托卡马克等离子体湍流与输运研究 [D]. 成都: 核工业西南物理研究院, 2016.
[23] Xiao W W, Ding X T, Liu Z T, et al. Measurement of turbulence propagation velocity using doppler reflectometer on HL-2A tokamak [J]. Plasma Science &Technology, 2008, 10(4): 403-406.
[24] Duan X R, Ding X T, Dong J Q, et al. An overview of recent HL-2A experiments [J]. Nucl. Fusion, 2013, 53(10): 587-593.
[25] Zhou Y, Deng Z C, Li Y G, et al. Multi-channel far-infrared HL-2A interferometer-polarimeter [J]. Rev.Sci. Instrum., 2012, 83(10): 10E336.
[26] Li Y G, Zhou Y, Li Y, et al. A new high sensitivity far-infrared laser interferometer for the HL-2A tokamak[J]. Rev. Sci. Instrum., 2017, 88(8): 083508.