Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously.This allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients duri...Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously.This allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients during heat wave propagation,etc.A drawback of many present-day systems is that they use a fixed frequency difference between the probing frequencies.Hence,although the central probing frequency can be varied,the probing frequency difference is usually fixed.The new design presented in this work uses an advanced microwave generation and detection scheme,which allows for arbitrary probing frequencies and probing frequency separations.展开更多
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
基金funding from the Euratom research and training programme 2014-2018 and2019-2020 under grant agreement No.633053。
文摘Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously.This allows for the investigation of fast timescales during L-H transitions,I-phases,I-mode bursts,transients during heat wave propagation,etc.A drawback of many present-day systems is that they use a fixed frequency difference between the probing frequencies.Hence,although the central probing frequency can be varied,the probing frequency difference is usually fixed.The new design presented in this work uses an advanced microwave generation and detection scheme,which allows for arbitrary probing frequencies and probing frequency separations.
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.
