Currents 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 of different physical nature. Besides known Pfirsch-Schlüter (PS) currents and thermoelectric currents, so-called PCC (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 particular, current flowing to the outer plate in the private flux region (PFR), opposite to thermolelectric current is predicted for the standard single-null configuration and favorable direction of ∇B drift (∇B drift of ions is directed towards active X-point). In addition, a pair of currents to and away from the outer plate should flow. In the single-null configuration they are often masked by a larger thermoelectric current, however for the connected double null (CDN) case, where thermoelectric current is strongly reduced due to less temperature asymmetry, these currents dominate. The suggested physical model is supported by results of simulations performed with SOLPS-ITER transport code. Simulations were done for ASDEX-Upgrade (AUG), L-mode , single-null configurations, and for Globus-M H-mode, both disconnected and connected double null configurations. Results of the simulations are compared with probe measurements for AUG and Globus-M tokamaks, and reasonable agreement has been found.

分析了托卡马克刮除层（SOL）中的电流结构。结果表明，在实验中测得的极向电流是几种物理性质不同的电流的组合。除了已知的Pfirsch-Schlüter（PS）电流和热电流之外，还分析了流入/流出分流器板的所谓PCC（板关闭电流）。后者关闭SOL中以及X点以下/上方的径向电流。具体地，流向在私人通量区域（PFR）的外板电流，相反thermolelectric电流预测∇的标准单零配置和有利的方向乙漂移（∇乙离子的漂移直接指向主动X点）。另外，应该有一对流入和流出外板的电流。在单零点配置中，它们通常被较大的热电电流掩盖，但是对于连接的双零点（CDN）情况，由于较低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传输代码执行的模拟结果支持。对ASDEX-Upgrade（AUG），L模式，单空配置以及对于Globus-M H模式进行了仿真，包括断开和连接的双空配置。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。