The helium effects in Chinese developed CN-G01 beryllium are important issues for its use in nuclear energy systems. In this work, the CN-G01 beryllium samples were irradiated with helium ions to fluences of 5.0 × 10¹⁶ ions/cm² to 1.0 × 10¹⁸ ions/cm² at room temperature and investigated by techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nano-indentation. It was found that the irradiation induced hardening of beryllium and the nano-hardness of the samples increased with increasing fluence of 5.0 × 10¹⁶ ions/cm² to 1.0 × 10¹⁷ ions/cm². When the fluence reached 5.0 × 10¹⁷ ions/cm² and 1.0 × 10¹⁸ ions/cm², helium irradiation induced serious surface blistering and its burst. TEM observation found that helium bubbles in the damage peak region became visible when the fluence reached 1.0 × 10¹⁷ ions/cm². With increasing fluence, helium bubbles became larger and connected into large cracks. The underlying physical mechanisms are discussed based on the helium behavior at low temperatures and the contributions of helium induced defects. This work will provide some new understanding on the irradiation resistance of CN-G01 beryllium and the helium effects in beryllium at low temperatures.

Synopsis LiTaO 3 single crystals were implanted by 100keV H-ion or He-ion. The results indicate that H-ion implantation creates a lower damage level than the He-ion implantation does, but the yield of oxygen vacancy produced by H-ion implantation is far higher than by He-ion implantation.

The granular flow spallation target is one of the important candidates for Accelerator-Driven Subcritical Transmutation Device. However, this type of target will be faced with many important problems, one of which is the collective friction and wear of granules in the target loop. As granular flow spallation target material, tungsten alloy balls have excellent comprehensive properties. This paper introduces some important problems in the research of the collective friction and wear of granules, as well as some obtained preliminary research results of tungsten alloy balls about collective friction and wear. At last, a perspective for the collective friction and wear of tungsten alloy balls for future research has been provided, especially the dependence of the formation of new layer on experimental conditions and the collective friction and wear behavior under irradiation conditions. It is hoped that more researchers will participate in this research field and more new discoveries to look forward to in the future.