Radiative cooling properties of He-defected tungsten with fiber-form nanostructured surface

The radiative cooling capability of tungsten with a fiber-form nanostructure is evaluated precisely using an electron-beam power system. It is found that the total emissivity of black nanostructured tungsten is very close to 1.0, meaning an almost complete black body. The discrepancies in the determination of the total emissivity between the electron-beam method and a fixed biasing procedure are discussed in terms of the power transmission through the plasma sheath, focusing on the ion energy reflection and cooling associated with electron emission.