Simulation of thermionic electron emission effect on the magnetized sheath near the target of tungsten

The high confinement mode (H-mode) is a preferred operation of tokamak devices in the future, but burst edge localized (ELM) will sharply increase heat load deposited on divertor target,raising target temperature rapidly and strengthening surface thermionic emission. In this paper, one-dimensional fluid model used to simulate influence electron emission characteristics magnetized sheath. results show that amplitude float potential electric field strength both decrease under action thermal Plenty electrons leave target, resulting region with negative charge density near plate, sheath divided into two parts: ion sheath, rise temperature, accumulated front also increase, distribution non-monotonic, “virtual cathode” structure appears. reverse formed confine leaving slow down movement, leading energy target. With angle between magnetic normal, proportion thickness increase. virtual cathode decreases, required form rises.