Damage study and comparison the effects of high-energy pulsed-protons of plasma focus device with low-energy protons of glow discharge plasma of tokamak

Abstract

This work investigates and compares the effects of high-energy, short-pulsed proton irradiation with low-energy, continuous proton beam on tungsten (W) surface. For this purpose, a W specimen was irradiated in 20 shots of plasma focus device with fluence of 5.2 × 1019 ions m−2, while another specimen was exposed to glow discharge (GD) plasma for 2.5 h with fluence of 2 × 1022 ions m−2. Lee Code was used to obtain the ion beam characteristics produced in the plasma focus device. SEM image was taken from the irradiated specimens before and after irradiation. Small blisters were detected on the surface of W irradiated with high-energy proton pulses, covering the entire surface of W. Larger blisters created by merging the small blisters were also observed. Small cracks were also created at the surface of W irradiated with high-energy ions. At the surface of W irradiated with the GD plasma, very large blisters were observed in the order of a few micrometers. In addition, fuzzy nanostructures can be seen on the W surface, which are grown in the island form. The XRD analysis was used to investigate the effects of radiation on the W crystal structure. Raw samples and samples irradiated with high-energy protons and low-energy protons were analyzed by the XRD. The results showed that the peaks in the XRD pattern of W samples irradiated with high energy protons were shifted to higher angles than those irradiated with low-energy protons. The peak intensity of the samples irradiated with high energy ions has significantly decreased.