Obtaining acceptable conditions at the divertor targets of a next-step fusion experiment based on the tokamak concept is expected to be particularly challenging because of the small predicted value of the plasma power exhaust channel width. An increased confidence in this prediction is important to forestall any power exhaust issue and in developing corresponding divertor solutions. With the present prediction relying on empirical scaling laws based on data from six tokamaks, this letter tests these scaling laws on an additional device, the TCV tokamak. Estimates of the exhaust channel width, λ _q , based on Thomson scattering measurements of the electron temperature and density profiles, correlate well with outer target infrared thermography. Reasonable agreement with multi-device scaling laws is found only when including both the power crossing the separatrix and the Greenwald density fraction as regression parameters. TCV’s λ _q is 2 to 3 times smaller than in spherical tokamaks for the same value of the poloidal field. The inclusion of TCV data in the scaling laws would, therefore, require the retention of an explicit aspect ratio dependence, with consequences for all other dependencies.

由于等离子功率排气通道宽度的预测值较小，因此基于托卡马克概念，在下一步聚变实验的分流器目标处获得可接受的条件预计将特别具有挑战性。增强对这一预测的信心对于防止任何动力排放问题和开发相应的分流器解决方案都很重要。由于目前的预测依赖于基于六个托卡马克数据的经验缩放定律，因此这封信将在另一台设备TCV托卡马克上测试这些缩放定律。排气通道宽度的估计，λ _q 基于电子温度和密度分布图的汤姆森散射测量结果，与外部目标红外热像图相关性很好。仅当同时包含通过交叉点的功率和格林瓦尔德密度分数作为回归参数时，才能找到与多设备缩放定律的合理一致性。TCV的λ _q比球形托卡马克的极向场的相同值小2到3倍。因此，将TCV数据包含在缩放定律中将需要保留显式的宽高比依赖性，并对所有其他依赖性产生影响。