Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations,with wavenumbers according to incident frequency and relative direction.Th...Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations,with wavenumbers according to incident frequency and relative direction.This way,a density fluctuation spectrum is measured.However,the correspondence between fluctuation power and scattered microwave power is strongly nonlinear.Studying these processes numerically therefore requires fullwave simulations(IPF-FD3 D),with density fluctuations supplied by a separate plasma turbulence code(GENE).Earlier such attempts suffered from the low number of data points in the‘interesting’part of the spectrum,where a power law had to be fitted to 4 or 5 points.This has been overcome with recent simulations,which now show a much better agreement with experimental data.展开更多
In this work,Doppler reflectometry(DR)and radial correlation DR(RCDR)nonlinear scattering effects are studied using full-wave modeling with a set of representative FT-2 tokamak turbulence as inputs.Narrowing of the RC...In this work,Doppler reflectometry(DR)and radial correlation DR(RCDR)nonlinear scattering effects are studied using full-wave modeling with a set of representative FT-2 tokamak turbulence as inputs.Narrowing of the RCDR correlation function and widening of the DR poloidal wavenumber spectrum are demonstrated.An effect on the dependence of the DR signal frequency shift on the probing wavenumber is found,namely,this dependence‘linearizing’in the nonlinear scattering regime.Nonlinear effects are shown to be weaker for O-mode probing than for X-mode probing,while a faster transition to nonlinear regime is demonstrated for RCDR compared to DR in both probing scenarios.展开更多
基金support by the state of Baden-Württemberg through bw HPCfunding from the Euratom research and training program 2014-2018 and 2019-2020 under grant agreement No.633053。
文摘Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations,with wavenumbers according to incident frequency and relative direction.This way,a density fluctuation spectrum is measured.However,the correspondence between fluctuation power and scattered microwave power is strongly nonlinear.Studying these processes numerically therefore requires fullwave simulations(IPF-FD3 D),with density fluctuations supplied by a separate plasma turbulence code(GENE).Earlier such attempts suffered from the low number of data points in the‘interesting’part of the spectrum,where a power law had to be fitted to 4 or 5 points.This has been overcome with recent simulations,which now show a much better agreement with experimental data.
基金Modeling of the O-mode DR signals was performed with the financial support of RFBR grant 18-32-00031Modeling of the X-mode DR signals was performed with the financial support of the Russian Science Foundation grant 17-1201110+3 种基金Measurements at the FT-2 tokamak were supported by the state contract of the Ioffe Institutethe work are supported by grants 316088 and 318314 of the Academy of Finlandpartially carried out within the framework of the French Federation for Magnetic Fusion Studies(FR-FCM)the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No.633053。
文摘In this work,Doppler reflectometry(DR)and radial correlation DR(RCDR)nonlinear scattering effects are studied using full-wave modeling with a set of representative FT-2 tokamak turbulence as inputs.Narrowing of the RCDR correlation function and widening of the DR poloidal wavenumber spectrum are demonstrated.An effect on the dependence of the DR signal frequency shift on the probing wavenumber is found,namely,this dependence‘linearizing’in the nonlinear scattering regime.Nonlinear effects are shown to be weaker for O-mode probing than for X-mode probing,while a faster transition to nonlinear regime is demonstrated for RCDR compared to DR in both probing scenarios.
