Current structure in the scrape-off layer (SOL) of a tokamak is analyzed. It is demonstrated that poloidal currents measured in the experiments are a combination of several current types with different physical nature. Besides the known Pfirsch–Schlter currents and thermoelectric currents, so-called plate closing currents flowing to/from the divertor plates are also analyzed. The latter close radial currents in the SOL and below/above the X-point in the SOL and private flux region (PFR). In particular, the current flowing to the outer plate in the PFR, opposite to the thermoelectric current, is predicted for the standard single-null configuration and favorable direction of drift. In addition, a pair of currents should flow to and away from the outer plate. In the single-null configuration, they are often masked by a larger thermoelectric current. However, for the connected double null (CDN) case, where the thermoelectric current is strongly reduced due to smaller temperature asymmetry, these currents dominate. The suggested physical model is supported by the results of simulations performed with the SOLPS-ITER transport code. Simulations were done for ASDEX Upgrade (AUG), L- and H-modes, single-null configurations, and for Globus-M H-mode, both disconnected and CDN configurations. Results of the simulations are compared with probe measurements for AUG and Globus-M tokamaks, and reasonable agreement has been found. The role of parallel currents in the formation of the potential maximum/minimum in the vicinity of the X-point for strongly detached regimes is also analyzed.

分析了托卡马克刮除层（SOL）中的当前结构。结果表明，在实验中测得的极向电流是几种具有不同物理性质的电流的组合。除了已知的Pfirsch–Schlter电流和热电流之外，还分析了流入/流出分流器板的所谓的板闭合电流。后者关闭SOL中的径向电流，并在SOL和专用磁通量区域（PFR）中X点以下/上方。特别是，对于标准的单空配置和良好的方向，预测了在PFR中与热电流相反流向外板的电流。漂移。另外，应该有一对电流流入和流出外板。在单零配置中，它们通常被较大的热电流掩盖。但是，对于连接的双零点（CDN）情况，由于较小的温度不对称性导致热电电流大大降低，因此这些电流占主导地位。建议的物理模型由SOLPS-ITER传输代码执行的仿真结果支持。针对ASDEX升级（AUG），L模式和H模式，单空配置以及对于Globus-M H模式进行了仿真，包括断开和CDN配置。将模拟结果与AUG和Globus-M托卡马克的测头进行了比较，并找到了合理的协议。并联电流在电势附近形成最大/最小电位的作用还分析了强分离体制的X点。