The correlation of edge plasma current, electric field and divertor condition in tokamak

The particle transport in divertor region of current size tokamak can be affected by electric field (E) significantly through the E x B drift. The plasma current, which is associated with drifts closely, affects E. In this work, the SOLPS-ITER code package is used to evaluate the influence of divertor regime, plasma current, toroidal magnetic field B-t direction on the electric field as well as divertor plasma. It is found that the poloidal current (j(x)) is dominated by parallel current, while the radial current (j(y)) mainly consists of diamagnetic and ion-neutral friction current near the target. The divertor regime plays an important role in electric field. (i) The poloidal electric field (E-x) is mainly affected by the electron density (n(e)) and temperature (T-e) in high recycling regime, and the parallel plasma current (j(vertical bar vertical bar)) plays an important role in E-x in detached regime. (ii) The radial electric field (E-y) is reduced significantly as divertor varies from high recycling regime to detached regime. It is also found that the B-t direction affects E-x and E-y in the divertor region significantly with low upstream density, while the role is weakened with high upstream density. The divertor asymmetry is also evaluated in different B-t with low/high upstream density. The dependence of E on divertor regime and B-t direction, and the corresponding impact on particle transport and divertor plasma are systemically studied and are important for steady-state discharge in current size tokamak.

Automated summary

This study evaluates the particle transport in the divertor region of a current size tokamak and investigates the influence of divertor regime, plasma current, and toroidal magnetic field direction on electric field and divertor plasma using the SOLPS-ITER code package. The results show that electron density and temperature affect the poloidal electric field, while the parallel plasma current plays a significant role in detached regime. The radial electric field decreases as the divertor regime changes. Furthermore, the magnetic field direction has a significant impact on the electric field, particularly at low upstream density.