Emission from Tungsten Nanostructured Tendril Bundles under Local Thermal Load

Unipolar arcing is a negative phenomenon which takes place during the plasma interaction with the first wall of thermonuclear devices. The mechanisms of arc initiation are still unclear. Formation of nanostructured tendril bundles is possible on the surface of plasma-facing tungsten, and field emission from such structure is expected to be rather high. Moreover such structure can be easily overheated and thermofield emission in this case could start. We show that field emission from such nanostructures is much higher than from tungsten fuzz or pure tungsten, and fusion-relevant heating conditions may lead to steady state thermofield current emission.