Surface modification at tungsten and tungsten coated graphite due to low energy and high fluence plasma and laser pulse irradiation

We have investigated the influence of low energy helium and hydrogen/deuterium plasma irradiation to tungsten or tungsten coated graphite samples. The experimental conditions of helium hole/bubble formation and hydrogen blister formation were summarized. The tungsten coated graphite exposed to a helium plasma shows different surface modification from those of bulk tungsten. We also demonstrated a transient heat load onto a damaged tungsten surface due to a helium plasma exposure by a laser-beam irradiation. Simultaneous helium plasma and laser pulse irradiations lead to a further roughing of the tungsten surface.