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学术报告
题目1：Studies of Lower Hybrid Range of Frequencies Actuators in the ARC Device
报告人：P.T. Bonoli (PSFC, MIT)
时间：11月13日（星期一）下午2：30
地点：4号楼6楼中间会议室
摘要：
High field side (HFS) placement of lower hybrid range of frequencies (LHRF) actuators is attractive from both the standpoint of a more quiescent scrape off layer (SOL) and from the improved LH wave accessibility and penetration to higher electron temperature that results from the higher magnetic field on the HFS [1]. The resulting profiles of LH current drive (LHCD) are also more suitable for advanced tokamak (AT) operation where it is most desirable to provide a significant (~ 20-30%) contribution to the total current density with a broad profile extending from r/a ~ 0.5-0.85. Here we re-assess HFS LHCD in the ARC device [2] using a hierarchy of LHCD models that include an adjoint treatment of the Fokker Planck equation combined with a 1D (in parallel velocity space) plus ray tracing calculation for the LH power absorption and a ray tracing plus 3D Fokker Planck calculation. It is found that 2D velocity space effects due to pitch angle scattering give rise to important differences between the 1D and 2D LH power absorption calculations.
[1] B. LaBombard et al, Nucl. Fusion 55, 053020 (2015).
[2] B. Sorbom et al, Fus. Eng. Design 100, 378 (2015).
题目2：From core to coax: extending core RF modelling to include SOL, Antenna, and PFC
报告人：S. Shiraiwa (PSFC, MIT)
时间：11月13日（星期一）下午3：30
地点：4号楼6楼中间会议室
摘要：A new technique for the calculation of RF waves in toroidal geometry enables the simultaneous incorporation of antenna geometry, plasma facing components (PFCs), the scrape off-layer (SOL), and core propagation. Traditionally, core RF wave propagation and antenna coupling has been calculated separately both using rather simplified SOL plasmas. The new approach, instead, allows capturing wave propagation in the SOL and its interactions with non-conforming PFCs permitting self-consistent calculation of core absorption and edge power loss. Our approach combines the field solutions obtained from a core spectral code and an edge FEM code via surface admittance-like matrix. The main motivating insight for this domain partitioning is that the core plasma region requires a hot plasma dielectric while the open field line region in SOL needs only a cold plasma dielectric but requires high fidelity to geometrical complexity. Our approach was verified using the TORIC core ICRF spectral code and the commercial COMSOL FEM package, and was extended to 3D torus using the open-source scalable MFEM library. For the first time, the capability of modeling RF wave in geometrically complicated antenna structure together with a hot core plasma was demonstrated and was applied to the field aligned antennas on Alcator C-Mod. Our approach can be used also to model non-axisymmetric plasmas such as a stellarator, thus potentially providing an universal powerful tool to investigate far and near field impurity generation from RF sheaths and a breakdown issue from antenna electric fields.
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