Core and edge turbulences were measured by Langmuir probe arrays in the KT-5C tokamak plasma.The radial wavenumber spectra show a quasimode like structure which results in a net radial outward propagation of the turbu...Core and edge turbulences were measured by Langmuir probe arrays in the KT-5C tokamak plasma.The radial wavenumber spectra show a quasimode like structure which results in a net radial outward propagation of the turbulent fluctuations.The measured fluctuation levels and wave action fluxes are in good agreement with model predictions by Mattor et al.,suggesting that drift wave propagation could be a source of edge turbulence.展开更多
Power spectrum and the probability distribution function(PDF)of the turbulence-induced particle fluxΓin the velocity shear layer of the HT-6M edge region have been measured and analysed.Three regions of frequency dep...Power spectrum and the probability distribution function(PDF)of the turbulence-induced particle fluxΓin the velocity shear layer of the HT-6M edge region have been measured and analysed.Three regions of frequency dependence(f0,f-1,f-4)have been observed in the spectrum of the flux.The PDF of the flux displays aΓ-1 scaling over one decade inΓ.Using the rescaled-range statistical technique,we find that the degree of the self-similarity(Hurst exponent)of the particle flux in the measured region ranges from 0.64 to 0.83.All of these results may mean that the plasma transport is in a state characterized by the self-organized criticality.展开更多
Time and space resolved measurements of the radial electric field(Er)have been conducted during the electrode biasing experiments on the KT-5C tokamak.The suppression of the turbulent transport with the change of Er i...Time and space resolved measurements of the radial electric field(Er)have been conducted during the electrode biasing experiments on the KT-5C tokamak.The suppression of the turbulent transport with the change of Er induced by the biased electrode is observed.It is found that the poloidal flow contributes to the main part of the Er,and the change of the poloidal flow has a lead of about 20μs to the formation of Er.These observations suggest that a radial current,responding to an induced voltage on the electrode,drives a poloidal flow which in turn drives the radial electric field.展开更多
Power spectra of electron density and floating potential fluctuations in the velocity shear layer of the HT-6M edge region have been measured and analysed.All the spectra have three distinct frequency regions with the...Power spectra of electron density and floating potential fluctuations in the velocity shear layer of the HT-6M edge region have been measured and analysed.All the spectra have three distinct frequency regions with the spectral decay indices typical of self-organized criticality systems(0,-1 and-4)when Doppler shift effects induced by the plasma E x B flow velocity have been taken into account.These results are consistent with the predictions of the self-organized criticality models,which may be an indication of edge plasma turbulence in the HT-6M tokamak evolving into a critical state independent of local plasma parameters.展开更多
Features of a low frequency ion mode were observed together with the electron drift wave type fluctuations by a Langmuir probe array in the bulk plasma inside the velocity shear layer in the KT-5C tokamak.The measured...Features of a low frequency ion mode were observed together with the electron drift wave type fluctuations by a Langmuir probe array in the bulk plasma inside the velocity shear layer in the KT-5C tokamak.The measured ion mode wavenumber,scaling of the ion mode with chord-averaged density,and the estimatedηi value suggest that the observed ion mode may be the theoretically predictedηi mode driven by ion temperature gradient.展开更多
It is found on KT-5C tokamak that an edge fluctuation mode can be excited by using a pair of floating Langmuir probes.This mode is propagating along the magnetic field with its amplitude decreasing drastically when it...It is found on KT-5C tokamak that an edge fluctuation mode can be excited by using a pair of floating Langmuir probes.This mode is propagating along the magnetic field with its amplitude decreasing drastically when it is off the magnetic field line.Preliminary feedback experiments show that the broadband edge turbulence can be reduced or enhanced depending upon the phase shift of the feedback network.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.19675036,19635020the Doctoral Training Foundation of National Education Commission of China and Chinese Academy of Sciences.
文摘Core and edge turbulences were measured by Langmuir probe arrays in the KT-5C tokamak plasma.The radial wavenumber spectra show a quasimode like structure which results in a net radial outward propagation of the turbulent fluctuations.The measured fluctuation levels and wave action fluxes are in good agreement with model predictions by Mattor et al.,suggesting that drift wave propagation could be a source of edge turbulence.
基金Supported by the National Natural Science Foundation of China under Grants Nos.19675036the Research Fund for the Doctoral Program of Higher Education(1999035809).
文摘Power spectrum and the probability distribution function(PDF)of the turbulence-induced particle fluxΓin the velocity shear layer of the HT-6M edge region have been measured and analysed.Three regions of frequency dependence(f0,f-1,f-4)have been observed in the spectrum of the flux.The PDF of the flux displays aΓ-1 scaling over one decade inΓ.Using the rescaled-range statistical technique,we find that the degree of the self-similarity(Hurst exponent)of the particle flux in the measured region ranges from 0.64 to 0.83.All of these results may mean that the plasma transport is in a state characterized by the self-organized criticality.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19635020,19675036,19775046the Chinese Academy of Sciences,and the National Doctoral Training Foundation under Grant Nos.9535806,9803810.
文摘Time and space resolved measurements of the radial electric field(Er)have been conducted during the electrode biasing experiments on the KT-5C tokamak.The suppression of the turbulent transport with the change of Er induced by the biased electrode is observed.It is found that the poloidal flow contributes to the main part of the Er,and the change of the poloidal flow has a lead of about 20μs to the formation of Er.These observations suggest that a radial current,responding to an induced voltage on the electrode,drives a poloidal flow which in turn drives the radial electric field.
基金Sponsored by the National Natural Science Foundation of China under Grant Nos.19675036 and 19635020the Research Fund for the Doctoral Programme of Higher Education under Grant No.1999035809the Chinese Academy of China.
文摘Power spectra of electron density and floating potential fluctuations in the velocity shear layer of the HT-6M edge region have been measured and analysed.All the spectra have three distinct frequency regions with the spectral decay indices typical of self-organized criticality systems(0,-1 and-4)when Doppler shift effects induced by the plasma E x B flow velocity have been taken into account.These results are consistent with the predictions of the self-organized criticality models,which may be an indication of edge plasma turbulence in the HT-6M tokamak evolving into a critical state independent of local plasma parameters.
基金Supported by the National Natural Science Foundation of China under Grant No.19275041the Doctoral Training Foundation of National Education Commission of China,and the Chinese Academy of Sciences.
文摘Features of a low frequency ion mode were observed together with the electron drift wave type fluctuations by a Langmuir probe array in the bulk plasma inside the velocity shear layer in the KT-5C tokamak.The measured ion mode wavenumber,scaling of the ion mode with chord-averaged density,and the estimatedηi value suggest that the observed ion mode may be the theoretically predictedηi mode driven by ion temperature gradient.
基金Supported by the Fund of the Chinese Academy of Sciences,and the National High Technology Program of China.
文摘It is found on KT-5C tokamak that an edge fluctuation mode can be excited by using a pair of floating Langmuir probes.This mode is propagating along the magnetic field with its amplitude decreasing drastically when it is off the magnetic field line.Preliminary feedback experiments show that the broadband edge turbulence can be reduced or enhanced depending upon the phase shift of the feedback network.
