Study on pulse shape dependence of tungsten mass erosion under disruption-like heat load

Abstract

We have studied pulse waveform dependence of tungsten mass erosion under disruption-like heat loads. In the experiment, tungsten samples were placed in a vacuum chamber and irradiated by a disruption-like heat load using a 1064 nm Nd: YAG laser. Mass erosion of tungsten samples by laser irradiation was measured by a microbalance. Laser intensity (up to 6.2 GW/m2), pulse duration (4 ms–5 ms), and pulsed laser waveform were changed as parameters. Five types of pulsed laser waveforms were used to investigate the mass erosion of tungsten; Positive Ramp, Symmetric Ramp, Negative Ramp, Half Amp Square, Half Width Square. Among these waveforms, the largest mass erosion was observed in Half Width Square under the same absorbed energy condition. Also, when the volume of the molten layer is sufficiently large, the mass erosion will be greater due to evaporation of tungsten and the release of droplets.