A branch of high-frequency Alfvenic modes is observed on the HL-2A tokamak.The electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam heating.Its mode frequency keeps almost unchanged ...A branch of high-frequency Alfvenic modes is observed on the HL-2A tokamak.The electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam heating.Its mode frequency keeps almost unchanged or presents a slow-sweeping behavior,depending on the detail current evolution.The poloidal and toroidal mode numbers are𝑚m/n=1/1.The mode has a quite short duration(≤20 ms)and usually appears 5-10 ms after the neutral beam being injected into the plasma.Hybrid simulations based on M3D-K have also been carried out.The result suggests that co-passing energetic particles are responsible for the mode excitation.The simulated mode structures are localized nearby location of minimum safety factor(q_(min))and agree with the structures obtained through tomography of soft x-ray arrays.Further,the modes are localized in the continuum gap and their frequencies increase with variation of𝑞min in a wide range.Last but not least,the characteristic of unchanged frequency on experiment is also reproduced by the nonlinear simulation with a fixed safety factor.All those evidences indicate that the𝑛n=1 high-frequency mode may belong to a reversed shear Alfven eigenmode.展开更多
By means of one photon absorption laser-induced resonance fluorescence at 599.5 nm the relative concentrations of amidogen(NH_(2))radical in the ammonia(NH_(3))radio-frequency(rf)plasma source were measured under diff...By means of one photon absorption laser-induced resonance fluorescence at 599.5 nm the relative concentrations of amidogen(NH_(2))radical in the ammonia(NH_(3))radio-frequency(rf)plasma source were measured under different discharge pressures and rf powers.The time dependence of the fluorescence which comes from the radiation 101-211 of the P-branches of the Σ vibronic sub-bands can be described by a single-exponential decay.The decay time of NH_(2)(A2A1)Σ(0,9,0)rovibronic state was determined.The spatial dependence of the NH_(2) density in discharge tube was measured.展开更多
基金supported by the National Key R&D Program of China(Grant No.2019YFE03020000)the National Natu ral Science Foundation of China(Grant No.12125502)+1 种基金the Sichuan Science and Technology Program(Grants No.2020JDJQ0070)the Natural Science Foundation of Sichuan(Grant No.2022NSFSC1823).
文摘A branch of high-frequency Alfvenic modes is observed on the HL-2A tokamak.The electromagnetic mode can be driven unstably in the plasma with an off-axis neutral beam heating.Its mode frequency keeps almost unchanged or presents a slow-sweeping behavior,depending on the detail current evolution.The poloidal and toroidal mode numbers are𝑚m/n=1/1.The mode has a quite short duration(≤20 ms)and usually appears 5-10 ms after the neutral beam being injected into the plasma.Hybrid simulations based on M3D-K have also been carried out.The result suggests that co-passing energetic particles are responsible for the mode excitation.The simulated mode structures are localized nearby location of minimum safety factor(q_(min))and agree with the structures obtained through tomography of soft x-ray arrays.Further,the modes are localized in the continuum gap and their frequencies increase with variation of𝑞min in a wide range.Last but not least,the characteristic of unchanged frequency on experiment is also reproduced by the nonlinear simulation with a fixed safety factor.All those evidences indicate that the𝑛n=1 high-frequency mode may belong to a reversed shear Alfven eigenmode.
基金Supported by the National Natural Science Foundation of China under Grant No.19875083.
文摘By means of one photon absorption laser-induced resonance fluorescence at 599.5 nm the relative concentrations of amidogen(NH_(2))radical in the ammonia(NH_(3))radio-frequency(rf)plasma source were measured under different discharge pressures and rf powers.The time dependence of the fluorescence which comes from the radiation 101-211 of the P-branches of the Σ vibronic sub-bands can be described by a single-exponential decay.The decay time of NH_(2)(A2A1)Σ(0,9,0)rovibronic state was determined.The spatial dependence of the NH_(2) density in discharge tube was measured.
