题 目： Development of TRIMEG code and Full-f and delta-f gyrokinetic particle simulations in tokamak plasmas
时 间： 2023年05月12日（周五） 下午 14：30
地 点： 九号会议室
摘 要：TRIMEG code has been developed in recent years, focusing on several physics models and numerical methods such as the triangular mesh, finite element method, gyrokinetic kinetic electrons and electromagnetic physics. Recently, full f gyrokinetic simulations have attracted intensive efforts recently. In this work, we focus on the development of the particle-in-cell scheme and its application to the studies of Alfvén waves and energetic particle (EP) physics in tokamak plasmas. The δf and full f schemes are formulated on the same footing adopting mixed variables and the pullback scheme for electromagnetic problems. The TRIMEG-GKX code has been upgraded using cubic spline finite elements and full f and δf schemes. The toroidal Alfvén eigenmode (TAE) driven by EPs has been simulated for the International Tokamak Physics activity (ITPA)-TAE case featured by a small electron skin depth ∼1.18 × 10−3 m, which is a challenging parameter regime for electromagnetic simulations, especially for the full f model. The simulation results using the δf scheme are in good agreement with previous work. Excellent performance of the mixed variable/pullback scheme has been observed for both full f and δf schemes. Simulations with mixed full f EPs and δf electrons and thermal ions demonstrate the good features of this novel scheme in mitigating the noise level. In full f model, the EP distribution using constants of motion is implemented for the proper description of the particle initial state to avoid the artificial density relaxation. The full f scheme is a natural choice for EP physics studies, which allows for large variations of EP profiles and distributions in velocity space, providing a powerful tool for kinetic studies using realistic experimental distributions related to intermittent and transient plasma activities. Its possible further application in the whole device simulations using TRIMEG code is discussed.
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