Temperature Range for Fiber-Form Nanostructure Growth on Molybdenum Surfaces due to Helium Plasma Irradiation

Abstract

Nanostructure formation on molybdenum surfaces due to helium plasma exposure is investigated, with a focus on determining the temperature band for the growth of fiber-form nanostructures. Precise temperature measurements can be obtained using thin thermocouples inserted into sheet specimens. The temperature range for nanostructure growth was determined to be 800 ∼ 1050 K under incident helium ion energies of 50 ∼ 100 eV and an ion flux of 2×1021 m−2 ·s−1. Surface morphologies near the upper and lower boundary temperatures differ from those of a standard fiber-form nanostructure. In a standard case, nano-fibers of molybdenum were found to have diameters of approximately 50 nm, whereas those of tungsten are half of the molybdenum fibers.