In this paper, singular value decomposition （SVD） as a filter-noise method is applied to electron cyclotron emission （ECE） diagnostic signals. The decomposed vectors contain the information about sawtooth such as ...In this paper, singular value decomposition （SVD） as a filter-noise method is applied to electron cyclotron emission （ECE） diagnostic signals. The decomposed vectors contain the information about sawtooth such as the temporal vectors that show the sawtooth period and the spatial vectors that indicate the inverse radius. The propagation of electron heat pulse is investigated from electron cyclotron emission signals by using the perturbation method in HT-7 tokamak. The heat diffusivities are obtained at different densities in ohmic plasmas. The special result is that the heat diffusivity becomes larger as the heat pulse propagates outwards from the outside of the inverse radius.展开更多
The propagation of heat pulses originating from sawtooth activity has been studied on the HT-7 tokamak. Two theoretical models are used for determining electron heat diffusivity from the experimental data measured by ...The propagation of heat pulses originating from sawtooth activity has been studied on the HT-7 tokamak. Two theoretical models are used for determining electron heat diffusivity from the experimental data measured by a diagnostic system of soft x-ray diode-array. The results show that one model called 'dipole model' is more suitable for HT-7 tokamak. In order to improve the signal-to-noise (S/N) ratio of the original signals, over a few tens of sawteeth are averaged to generate nice waveforms. The space-time evolution is found to be diffusive in character, which is consistent with the theoretical model. The electron heat diffusivity determined from heat pulse propagation is larger than that determined from background plasma power balance. The variation of Xe in different discharge phases has been also discussed.展开更多
It is found that in HT-7 ohmic plasma, main energy loss comes from electron heat conduction, hence quantitative data of electron heat diffusivity is a very important issue for investigation of electron heat transporta...It is found that in HT-7 ohmic plasma, main energy loss comes from electron heat conduction, hence quantitative data of electron heat diffusivity is a very important issue for investigation of electron heat transportation behavior in different target plasmas so as to get high performance plasma. A time-to-peak method of the heat pulse propagation originating from the sawtooth activity on the soft x-ray intensity signal has been adopted to experimentally determine electron heat diffusivity XeHP on the HT-7 tokamak. Aiming to improve the signal-to-noise (S/N) ratio of the original signal to get a stable and reasonable electron heat diffusivity XeHD value, some data processing methods, including average of tens of sawteeth, is discussed. The electron heat diffusivity XeHP is larger than XePB which is determined from the balance of background plasma power. Based on variation of the measured electron heat diffusivity XeHP, performances of different high confinement plasmas are analyzed.展开更多
文摘In this paper, singular value decomposition （SVD） as a filter-noise method is applied to electron cyclotron emission （ECE） diagnostic signals. The decomposed vectors contain the information about sawtooth such as the temporal vectors that show the sawtooth period and the spatial vectors that indicate the inverse radius. The propagation of electron heat pulse is investigated from electron cyclotron emission signals by using the perturbation method in HT-7 tokamak. The heat diffusivities are obtained at different densities in ohmic plasmas. The special result is that the heat diffusivity becomes larger as the heat pulse propagates outwards from the outside of the inverse radius.
基金The project supported by Meg-Science Engineering Item of the Chinese Academy of Sciences
文摘The propagation of heat pulses originating from sawtooth activity has been studied on the HT-7 tokamak. Two theoretical models are used for determining electron heat diffusivity from the experimental data measured by a diagnostic system of soft x-ray diode-array. The results show that one model called 'dipole model' is more suitable for HT-7 tokamak. In order to improve the signal-to-noise (S/N) ratio of the original signals, over a few tens of sawteeth are averaged to generate nice waveforms. The space-time evolution is found to be diffusive in character, which is consistent with the theoretical model. The electron heat diffusivity determined from heat pulse propagation is larger than that determined from background plasma power balance. The variation of Xe in different discharge phases has been also discussed.
基金The project supported by National Natural Science Foundation (Nos. 10375070, 10305012)and also supported partially by the core university program between China and Japan
文摘It is found that in HT-7 ohmic plasma, main energy loss comes from electron heat conduction, hence quantitative data of electron heat diffusivity is a very important issue for investigation of electron heat transportation behavior in different target plasmas so as to get high performance plasma. A time-to-peak method of the heat pulse propagation originating from the sawtooth activity on the soft x-ray intensity signal has been adopted to experimentally determine electron heat diffusivity XeHP on the HT-7 tokamak. Aiming to improve the signal-to-noise (S/N) ratio of the original signal to get a stable and reasonable electron heat diffusivity XeHD value, some data processing methods, including average of tens of sawteeth, is discussed. The electron heat diffusivity XeHP is larger than XePB which is determined from the balance of background plasma power. Based on variation of the measured electron heat diffusivity XeHP, performances of different high confinement plasmas are analyzed.
