Impurity Release from Tungsten Surface by Laser Heat Pulse Irradiation

The influence of a transient heat load on the formation of bubble and hole structures on tung- sten surface exposed to helium plasma is demonstrated using pulsed laser-beam irradiation in divertor simulator NAGDIS-II. It was confirmed that tungsten and helium atoms were released from tungsten sur- face right after the laser irradiation during exposure to helium plasma with using ICCD camera. SEM mi- crographs of the tungsten surface revealed that the formation of bubbles and holes was dramatically en- hanced due to transient temperature increase in response to the laser irradiation.