Recent EAST/DIII-D joint experiments on the high poloidal beta regime in DIII-D have extended operation with internal transport barriers (ITBs) and excellent energy confinement (H98y2 ~ 1.6) to higher plasma current, for lower q95 ⩽ 7.0, and more balanced neutral beam injection (NBI) (torque injection < 2 Nm), for lower plasma rotation than previous results (Garofalo et al, IAEA 2014, Gong et al 2014 IAEA Int. Conf. on Fusion Energy). Transport analysis and experimental measurements at low toroidal rotation suggest that the E × B shear effect is not key to the ITB formation in these high discharges. Experiments and TGLF modeling show that the Shafranov shift has a key stabilizing effect on turbulence. Extrapolation of the DIII-D results using a 0D model shows that with the improved confinement, the high bootstrap fraction regime could achieve fusion gain Q = 5 in ITER at ~ 2.9 and q95 ~ 7. With the optimization of q(0), the required improved confinement is achievable when using 1.5D TGLF-SAT1 for transport simulations. Results reported in this paper suggest that the DIII-D high scenario could be a candidate for ITER steady state operation.
近期EAST/DIII-D联合实验在DIII-D高极β模式下，将内部输运垒（ITB）和优异能量约束（H98y2 ~ 1.6）的运行范围扩展到了更高等离子体电流、更低q95（≤ 7.0）以及更平衡的中性束注入（NBI）（扭矩注入 < 2 N·m），对应比先前结果（Garofalo等，IAEA 2014；Gong等，IAEA 2014）更低的等离子体旋转。输运分析和实验测量表明，在低旋转条件下，E × B剪切效应并非这些高β放电中ITB形成的关键因素。实验与TGLF模拟均显示，Shafranov位移对湍流具有关键的稳定化作用。利用0D模型对DIII-D结果进行外推表明，在改善约束条件下，高自举电流份额 regime 可在ITER中实现聚变增益Q = 5，对应βN ~ 2.9和q95 ~ 7。通过优化q(0)，使用1.5D TGLF-SAT1输运模拟可实现所需的改善约束。本文结果表明，DIII-D高β方案可作为ITER稳态运行的候选方案。