Effect of gallium doping on bubbling and helium retention in aluminum exposed to low-energy helium plasma

TL;DR

This study investigates how gallium doping affects helium bubble formation and retention in aluminum exposed to low-energy helium plasma, revealing that Ga doping reduces bubble size, increases bubble density, and enhances helium release.

Contribution

It provides new insights into the effects of gallium doping on helium behavior in aluminum, showing significant changes in bubble morphology and helium desorption properties.

Findings

Ga doping results in smaller helium bubbles with higher density.

Helium desorption is significantly increased and occurs at lower temperature in Ga-doped aluminum.

Lattice distortion from Ga influences vacancy defects and helium retention.

Abstract

Surface bubbling and helium retention of pure aluminum and a solid solution of aluminum-gallium(Ga) alloy exposed to low-energy He plasma has been investigated with the fluence of 1.8E24 He/m2 at room temperature . Surface morphology observations show that after irradiation, the average size of He bubbles on Al-1.8 at.% Ga alloy is around 1.8 micro metre, smaller than that on pure Al. Ga doping noticeably increases the area density of the bubble. The thermal desorption spectroscopyshows that the release amount of He in Al-1.8 at.% Ga alloy is 1.77E21 He/m2, nearly three orders of magnitude higher than that in pure Al, whlie the He desorption peak of Al-1.8 at.% Ga alloy is 480 K, much lower than 580 K of pure Al. The results of slow positron annihilation spectroscopy (SPAS) indicate that the vacancy type defects were introduced by He plasma irradiation; and lattice distortion caused by Ga doping plays an important role in determining surface bubbling and He retention characteristics of Al-1.8 at.% Ga.