Increasing the heat and particle deposition on the divertor target plates is an effective approach for reducing the extremely high heat load. Future tokamak fusion devices are expected to have a deposition width on the order of a millimeter. Recently, a double-peaked distribution (DPD) pattern of particle deposition at the divertor target plates has been observed in both deuterium and helium plasma discharges in the Experimental Advanced Superconducting Tokamak, which can significantly spread the deposition width of heat and particle fluxes, and clearly shows a toroidal symmetric distribution. It has been found that the DPD behavior occurs not only in plasma discharges with lower hybrid wave (LHW) heating, but also with electron cyclotron resonance heating or neutral beam injection (NBI) heating alone. In addition, the DPD shows an obvious in–out asymmetry between the divertor target plates, which strongly depends on the toroidal field direction, i.e. it distinctly appears on the outer divertor plate in unfavorable B _t conditions, while shifting to the inner divertor plate under favorable B _t conditions. Meanwhile, the transition between the single-peaked distribution and the DPD is normally correlated with the line-averaged plasma density and the auxiliary heating power. The statistical results for the pure LHW heating discharge scheme show that the DPD behavior is significantly affected by both the plasma density and the heating power, i.e. the lower the ratio of the plasma density to the heating power, the more likely it is that DPD behavior will occur. The critical boundary lines between the DPD and non-DPD patterns are obtained with the line expressions ∼ 2P _LHW,abs + 1.4 and ∼ 3.33P _LHW,abs + 1 for the unfavorable and favorable B _t cases, respectively. Finally, the underlying physics is also discussed, suggesting that the electric field drifts and the local sheath boundary condition may exert a strong influence on the DPD.

增加偏滤器靶板上的热量和颗粒沉积是减少极高热负荷的有效方法。预计未来的托卡马克聚变装置的沉积宽度将达到毫米量级。最近，在实验先进超导托卡马克的氘和氦等离子体放电中观察到偏滤器靶板上颗粒沉积的双峰分布 (DPD) 模式，这可以显着扩展热量和颗粒通量的沉积宽度，并且清楚地显示了环形对称分布。已经发现 DPD 行为不仅发生在具有较低混合波 (LHW) 加热的等离子体放电中，而且还发生在单独的电子回旋共振加热或中性束注入 (NBI) 加热中。此外，B _t条件，同时在有利的B _t条件下转移到内部偏滤器板。同时，单峰分布和 DPD 之间的转变通常与线平均等离子体密度和辅助加热功率相关。纯LHW加热放电方案的统计结果表明，DPD行为受等离子体密度和加热功率的影响显着，即等离子体密度与加热功率的比值越低，DPD行为的可能性越大会发生。DPD 和非 DPD 图案之间的临界边界线通过线表达式∼ 2 P _LHW,abs + 1.4 和∼ 3.33 P 获得 _LHW,abs + 1 分别用于不利和有利的B _t情况。最后，还讨论了基础物理学，表明电场漂移和局部鞘层边界条件可能对 DPD 产生强烈影响。