Electron heat diffusivity inferred from the electron power balance was studied in the ohmically heated plasma on an HT-7 tokamak.The results obtained before and after siliconization were compared and it is found that ...Electron heat diffusivity inferred from the electron power balance was studied in the ohmically heated plasma on an HT-7 tokamak.The results obtained before and after siliconization were compared and it is found that the diffusivity is reduced obviously in the half of the outer region(r/a>0.5)after siliconization,which was the reason why energy confinement was improved after siliconization.展开更多
Ion cyclotron resonance heating experiments using antenna in the high field side(HFS)have been carried out on HT-7 in different target plasmas.Unlike a standard-mode conversion heating scheme with dominant electron he...Ion cyclotron resonance heating experiments using antenna in the high field side(HFS)have been carried out on HT-7 in different target plasmas.Unlike a standard-mode conversion heating scheme with dominant electron heating,anomalous ion heating and DD neutron fluxes higher than those estimated from thermal ions were observed in the present experiments with the ion-ion hybrid resonant layer near the center of plasma.The features of ion cyclotron range frequency(ICRF)antenna in HFS and experiments suggest that this is most probably due to the nonlinear 3/2 harmonic deuterium heating by the mode-converted ion Bernstein wave,which could produce a high energy tail on ion energy distribution.展开更多
The emission lines of B,C,O and Fe in tokamak plasma are reported.The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate a...The emission lines of B,C,O and Fe in tokamak plasma are reported.The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate atomic data.General agreement is obtained between the results of experiment and computation.Most of the lines in the spectra are identified,and the relative number density ratios of B,C,O and Fe are determined.It is found that the processes of line formation in our experiment are similar to those in the stellar coronae.The line-averaged electron density of the tokamak plasma is measured by the HCN laser,indicating a good agreement with the theoretical prediction by the density-dependent line ratio of Fe XXI.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
High spatial resolution measurements of the electrostatic Reynolds stress,radial electric field and poloidal phase velocity of fluctuations in the edge region of the HT-6M tokamak are carried out.The Reynolds stress s...High spatial resolution measurements of the electrostatic Reynolds stress,radial electric field and poloidal phase velocity of fluctuations in the edge region of the HT-6M tokamak are carried out.The Reynolds stress shows a radial gradient in proximity to the poloidal velocity shear.A comparison of the profiles between the Reynolds stress gradient and the poloidal velocity damping reveals some similarity in their magnitude and radial structure.These facts suggest that the turbulence-induced Reynolds stress may play a significant role in generating the poloidal flow in the plasma edge region.展开更多
The soft x-ray pulse-height-analysis technique is a conventional tool to measure electron temperature on tokamak.The soft x-ray spectra distortion due to energy resolution of detector will affect the temperature and i...The soft x-ray pulse-height-analysis technique is a conventional tool to measure electron temperature on tokamak.The soft x-ray spectra distortion due to energy resolution of detector will affect the temperature and impurity concentration determination.To evaluate these effects,distorted spectra as functions of energy resolution are derived by numerical modeling.The results show that the low energy resolution detector can fit for the large-sized tokamak soft x-ray spectra.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
文摘Electron heat diffusivity inferred from the electron power balance was studied in the ohmically heated plasma on an HT-7 tokamak.The results obtained before and after siliconization were compared and it is found that the diffusivity is reduced obviously in the half of the outer region(r/a>0.5)after siliconization,which was the reason why energy confinement was improved after siliconization.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10725523 and 10721505.
文摘Ion cyclotron resonance heating experiments using antenna in the high field side(HFS)have been carried out on HT-7 in different target plasmas.Unlike a standard-mode conversion heating scheme with dominant electron heating,anomalous ion heating and DD neutron fluxes higher than those estimated from thermal ions were observed in the present experiments with the ion-ion hybrid resonant layer near the center of plasma.The features of ion cyclotron range frequency(ICRF)antenna in HFS and experiments suggest that this is most probably due to the nonlinear 3/2 harmonic deuterium heating by the mode-converted ion Bernstein wave,which could produce a high energy tail on ion energy distribution.
基金by the National Natural Science Foundation of China under Grant Nos 10821061,10876040,10925421 and 10734130the Chinese Academy of Sciences under Grant No KJCX2-YW-T01the National Basic Research Program of China under Grant No 2007CB815103.
文摘The emission lines of B,C,O and Fe in tokamak plasma are reported.The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate atomic data.General agreement is obtained between the results of experiment and computation.Most of the lines in the spectra are identified,and the relative number density ratios of B,C,O and Fe are determined.It is found that the processes of line formation in our experiment are similar to those in the stellar coronae.The line-averaged electron density of the tokamak plasma is measured by the HCN laser,indicating a good agreement with the theoretical prediction by the density-dependent line ratio of Fe XXI.
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.19675036 and 19635020the Research Fund for the Doctoral Program of Higher Education。
文摘High spatial resolution measurements of the electrostatic Reynolds stress,radial electric field and poloidal phase velocity of fluctuations in the edge region of the HT-6M tokamak are carried out.The Reynolds stress shows a radial gradient in proximity to the poloidal velocity shear.A comparison of the profiles between the Reynolds stress gradient and the poloidal velocity damping reveals some similarity in their magnitude and radial structure.These facts suggest that the turbulence-induced Reynolds stress may play a significant role in generating the poloidal flow in the plasma edge region.
文摘The soft x-ray pulse-height-analysis technique is a conventional tool to measure electron temperature on tokamak.The soft x-ray spectra distortion due to energy resolution of detector will affect the temperature and impurity concentration determination.To evaluate these effects,distorted spectra as functions of energy resolution are derived by numerical modeling.The results show that the low energy resolution detector can fit for the large-sized tokamak soft x-ray spectra.
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.
