Predictions of core plasma performance for the SPARC tokamak

SPARC is designed to be a high-field, medium-size tokamak aimed at achieving net energy gain with Ion Cyclotron Range-of-Frequencies (ICRF) as its primary auxiliary heating mechanism. Empirical predictions with conservative physics indicate that SPARC baseline plasmas would reach Q~11, well above its mission objective of Q>2. To build confidence that SPARC will be successful, physics-based integrated modeling has also been performed. The TRANSP code coupled with the theory-based TGLF turbulence model and EPED predictions for pedestal stability find that Q~9 is attainable in standard H-mode operation and confirms Q>2 operation is feasible even with adverse assumptions. In this analysis, ion cyclotron waves are simulated with the full wave TORIC code and alpha heating is modeled with the Monte-Carlo fast ion NUBEAM module. Detailed analysis of expected turbulence regimes with linear and nonlinear CGYRO simulations is also presented, demonstrating that profile predictions with the TGLF reduced model are in reasonable agreement.

SPARC是一款以离子回旋共振频段（Ion Cyclotron Range-of-Frequencies, ICRF）作为主要辅助加热手段，旨在实现净能量增益的高场中型托卡马克（tokamak）装置。基于保守物理框架的经验预测显示，SPARC的基准等离子体可实现Q≈11的聚变增益，远高于其Q>2的任务目标。为增强对SPARC项目可行性的信心，研究团队还开展了基于物理原理的集成建模工作。将TRANSP代码与理论驱动的TGLF湍流模型、针对等离子体基座稳定性的EPED预测结果耦合后，分析结果表明：标准H模式（H-mode）运行下可实现Q≈9的增益，且即便采用不利假设，Q>2的运行方案仍具备可行性。本次分析中，研究团队借助全波TORIC代码模拟离子回旋波，并通过蒙特卡洛快离子NUBEAM模块对阿尔法加热过程进行建模。此外，团队还通过线性与非线性CGYRO模拟对预期湍流状态开展了详细分析，结果表明采用TGLF简化模型得到的等离子体轮廓预测结果具备合理的一致性。