Owing to its high magnetic field, high power, and compact size, the SPARC experiment will operate with divertor conditions at or above those expected in reactor-class tokamaks. Power exhaust at this scale remains one of the key challenges for practical fusion energy. Based on empirical scalings, the peak unmitigated divertor parallel heat flux is projected to be greater than 10 GW m−2. This is nearly an order of magnitude higher than has been demonstrated to date. Furthermore, the divertor parallel Edge-Localized Mode (ELM) energy fluence projections (~11–34 MJ m−2) are comparable with those for ITER. However, the relatively short pulse length (~25 s pulse, with a ~10 s flat top) provides the opportunity to consider mitigation schemes unsuited to long-pulse devices including ITER and reactors. The baseline scenario for SPARC employs a ~1 Hz strike point sweep to spread the heat flux over a large divertor target surface area to keep tile surface temperatures within tolerable levels without the use of active divertor cooling systems. In addition, SPARC operation presents a unique opportunity to study divertor heat exhaust mitigation at reactor-level plasma densities and power fluxes. Not only will SPARC test the limits of current experimental scalings and serve for benchmarking theoretical models in reactor regimes, it is also being designed to enable the assessment of long-legged and X-point target advanced divertor magnetic configurations. Experimental results from SPARC will be crucial to reducing risk for a fusion pilot plant divertor design.

中文翻译：

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SPARC 中的分流器热通量挑战和缓解

由于其高磁场、高功率和紧凑的尺寸，SPARC 实验将在偏滤器条件下运行，该条件等于或高于反应堆级托卡马克的预期条件。这种规模的功率排放仍然是实用聚变能的主要挑战之一。根据经验比例，峰值未缓解偏滤器平行热通量预计大于 10 GW m-2。这几乎比迄今为止所证明的高出一个数量级。此外，偏滤器平行边缘局部模式 (ELM) 能量注量投影 (~11–34 MJ m-2) 与 ITER 的那些相当。然而，相对较短的脉冲长度（~25 s 脉冲，具有~10 s 平顶）提供了考虑不适合包括 ITER 和反应堆在内的长脉冲设备的缓解方案的机会。SPARC 的基线方案采用 ~1 Hz 的冲击点扫描来将热通量散布到大的偏滤器目标表面积上，从而在不使用主动偏滤器冷却系统的情况下将瓷砖表面温度保持在可容忍的水平内。此外，SPARC 操作提供了一个独特的机会来研究在反应堆级等离子体密度和功率通量下的偏滤器热排放缓解。SPARC 不仅将测试当前实验规模的限制并用于对反应堆制度中的理论模型进行基准测试，它还旨在评估长腿和 X 点目标先进偏滤器磁性配置。SPARC 的实验结果对于降低聚变试验工厂偏滤器设计的风险至关重要。