A new integrated technique for fast and accurate measurement of the quasi-optics, especially for the microwave/millimeter wave diagnostic systems of fusion plasma, has been developed. Using the LabVIEW-based comprehen...A new integrated technique for fast and accurate measurement of the quasi-optics, especially for the microwave/millimeter wave diagnostic systems of fusion plasma, has been developed. Using the LabVIEW-based comprehensive scanning system, we can realize not only automatic but also fast and accurate measurement, which will help to eliminate the effects of temperature drift and standing wave/multi-reflection. With the Matlab-based asymmetric two-dimensional Gaussian fitting method, all the desired parameters of the microwave beam can be obtained. This technique can be used in the design and testing of microwave diagnostic systems such as reflectometers and the electron cyclotron emission imaging diagnostic systems of the Experimental Advanced Superconducting Tokamak.展开更多
We compare three different methods to extract coherent modes from Doppler backscattering （DBS）, which are center of gravity （COG） of the complex amplitude spectrum, spectrum of DBS phase derivative （phase derivat...We compare three different methods to extract coherent modes from Doppler backscattering （DBS）, which are center of gravity （COG） of the complex amplitude spectrum, spectrum of DBS phase derivative （phase derivative method）, and phase spectrum, respectively. These three methods are all feasible to extract coherent modes, for example, geodesic acoustic mode oscillation. However, there are stilI differences between dealing with high frequency modes （several hundred kHz） and low frequency modes, （several kHz） hiding in DBS signal. There is a significant amount of power at low frequencies in the phase spectrum, which can be removed by using the phase derivative method and COG. High frequency modes are clearer by using the COO and the phase derivative method than the phase spectrum. The spectrum of DBS amplitude does not show the coherent modes detected by using COG, phase derivative method and phase spectrum. When two Doppler shifted peaks exist, coherent modes and their harmonics appear in the spectrum of DBS amplitude, which are introduced by the DBS phase.展开更多
An extraordinary-mode （X-mode） frequency-modulated continuous-wave （FMCW） profile reflectometer has been built on EAST. In the reflectometer, continuous waves with fre- quency sweeping from 12.5 GHz to 18 GHz were...An extraordinary-mode （X-mode） frequency-modulated continuous-wave （FMCW） profile reflectometer has been built on EAST. In the reflectometer, continuous waves with fre- quency sweeping from 12.5 GHz to 18 GHz were generated through a Hyperabrupt Tuned-varactor Oscillator （HTO） source and a four times active multiplier was used to increase the frequency to V-band （50 GHz to 72 GHz）. The polarization of horn lens antenna is perpendicular to the mag- netic field line at the edge plasmas. According to the V-band frequency range and polarization, the system cover density range from 0.5 x 1019m-3 to 3.0 x 1019m-3 （when toroidal magnetic field is 1.8 T）, with time resolution of 12.5 ~ 50 #s. The density profile could be calculated by assuming the edge profile through an empirical equation. The maximum spatial error deduced by the method is about 4 cm. This reflectometer has been successfully applied in 2010 autumn EAST campaign, the temporal evolution of density profiles was acquired during the low confine- ment mode to high confinement mode transition. The density pedestal of EAST Tokamak was observed and the top value and gradient of the density pedestal were estimated.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.10990211,11475173)the ITER Domestic Program of China(Grant Nos.2013GB106002,2014GB109002)
文摘A new integrated technique for fast and accurate measurement of the quasi-optics, especially for the microwave/millimeter wave diagnostic systems of fusion plasma, has been developed. Using the LabVIEW-based comprehensive scanning system, we can realize not only automatic but also fast and accurate measurement, which will help to eliminate the effects of temperature drift and standing wave/multi-reflection. With the Matlab-based asymmetric two-dimensional Gaussian fitting method, all the desired parameters of the microwave beam can be obtained. This technique can be used in the design and testing of microwave diagnostic systems such as reflectometers and the electron cyclotron emission imaging diagnostic systems of the Experimental Advanced Superconducting Tokamak.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10990210 and 11475173the National Magnetic Confinement Fusion Energy Program of China under Grant Nos 2013GB106002 and 2014GB109002
文摘We compare three different methods to extract coherent modes from Doppler backscattering （DBS）, which are center of gravity （COG） of the complex amplitude spectrum, spectrum of DBS phase derivative （phase derivative method）, and phase spectrum, respectively. These three methods are all feasible to extract coherent modes, for example, geodesic acoustic mode oscillation. However, there are stilI differences between dealing with high frequency modes （several hundred kHz） and low frequency modes, （several kHz） hiding in DBS signal. There is a significant amount of power at low frequencies in the phase spectrum, which can be removed by using the phase derivative method and COG. High frequency modes are clearer by using the COO and the phase derivative method than the phase spectrum. The spectrum of DBS amplitude does not show the coherent modes detected by using COG, phase derivative method and phase spectrum. When two Doppler shifted peaks exist, coherent modes and their harmonics appear in the spectrum of DBS amplitude, which are introduced by the DBS phase.
基金supported by National Natural Science Foundation of China(Nos.10990211,10835009 and 11105146)the ITER Domestic Program of China(Nos.2010GB107000,2013GB106002)Fundamental Research Funds for the Central Universities(No.WK2030040026)
文摘An extraordinary-mode （X-mode） frequency-modulated continuous-wave （FMCW） profile reflectometer has been built on EAST. In the reflectometer, continuous waves with fre- quency sweeping from 12.5 GHz to 18 GHz were generated through a Hyperabrupt Tuned-varactor Oscillator （HTO） source and a four times active multiplier was used to increase the frequency to V-band （50 GHz to 72 GHz）. The polarization of horn lens antenna is perpendicular to the mag- netic field line at the edge plasmas. According to the V-band frequency range and polarization, the system cover density range from 0.5 x 1019m-3 to 3.0 x 1019m-3 （when toroidal magnetic field is 1.8 T）, with time resolution of 12.5 ~ 50 #s. The density profile could be calculated by assuming the edge profile through an empirical equation. The maximum spatial error deduced by the method is about 4 cm. This reflectometer has been successfully applied in 2010 autumn EAST campaign, the temporal evolution of density profiles was acquired during the low confine- ment mode to high confinement mode transition. The density pedestal of EAST Tokamak was observed and the top value and gradient of the density pedestal were estimated.
