Overheating of Nanostructured Tendril Bundles due to Thermo-Field Emission

Field emission current accompanied by visualization of emission sites distribution was measured for nanostructured tendril bundles (NTB) on a tungsten surface. These structures are formed in linear simulators of plasma-surface interaction under helium plasma irradiation with Ne or N
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mixture, and unipolar arcing is often observed for such surfaces. It was shown that field emission current from NTB could be stable for a long period under constant electric field making these structures promising to use as flat cold cathodes. A numerical model was developed for calculating the thermo-field emission current and for checking the possibility of self-heating of the structures depending on their shape. Critical electric field values that lead to self- heating were estimated for different NTB shapes and compared with experimental results.