题 目： Role of isotopes in microturbulence from linear to saturated Ohmic confinement regimes
时 间： 2023年05月17日（周三） 下午 14：30
地 点： 聚变科学所二楼大会议室
摘 要： Key physical mechanisms behind the enigma of isotopic dependence of the energy confinement in tokamak fusion plasmas is identified. Mitigation of turbulence radial electric field intensity 〖|δE_r |〗^2 and associated poloidal δE × B fluctuating velocity with the radial correlation length l_cr∝M_i^0.11 strongly deviating from the gyro-Bohm scaling are demonstrated to be the dominant mechanism contributing to isotope effects. Three main contributors are identified, the deviation from gyro-Bohm scaling, zonal flow and trapped electron turbulence stabilization. Zonal flow enhances isotope effects primarily through reinforcing the inverse dependence of turbulence decorrelation rate on isotope mass with l_cr∝M_i^(-0.76), which is drastically different from the characteristic linear frequency. Gyrokinetic numerical calculations exhibit a fair agreement with experimental observations, particularly in the context of linear Ohmic confinement to saturated Ohmic confinement transition in the presence of isotopes.
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