Laser ablation technique is a novel method for obtaining a surface with a low secondary electron yield (SEY) that can mitigate electron cloud in high-energy accelerators. Before the installation of laser processed aluminum alloy, surface cleaning is of the essence to reduce the contaminations of ultra-high vacuum systems for providing appropriate pressure for beam operation consequently. Laser processed aluminum alloy is one of the crucial candidates for the vacuum system construction of future accelerators. Moreover, ultrasonic cleaning is an essential procedure for most materials applied in vacuum systems. Therefore, in order to verify the stability of the laser created structures by ultrasonic cleaning and evaluate the impact of the cleaning on the SEYs, the surface topographies, and the surface chemistries of laser treated aluminum alloy, SEY measurements and related tests were performed. After ultrasonic cleaning, the SEYs of laser treated aluminum alloy increased from 0.99, 1.05, and 1.16 to 1.43, 1.74, and 1.38, respectively. Compared to the surface roughness of uncleaned laser treated aluminum samples, the cleaned laser treated ones decreased from 10.7, 7.5, and 14.5 to 9.4, 6.9, and 12.9, respectively. The results indicate that ultrasonic cleaning can induce the SEY increase of laser processed aluminum alloy. The correlative mechanism between the surface morphology, the surface chemistry, and SEY increase were analyzed for the first time.

Secondary electron emission (SEE) inhibition and vacuum instability are two important issues in accelerators that may induce multiple effects in accelerators, such as power loss and beam lifetime reduction. In order to mitigate SEE and maintain high vacuum simultaneously, open-cell copper metal foam (OCMF) substrates with Ti-Zr-V-Hf non-evaporable getter (NEG) coatings are first proposed, and the properties of surface morphology, surface chemistry and secondary electron yield (SEY) were analyzed for the first time. According to the experimental results tested at 25 °C, the maximum SEY (${\delta }_{max}$) of OCMF before and after Ti-Zr-V-Hf NEG film deposition were 1.25 and 1.22, respectively. The XPS spectra indicated chemical state changes of the metal elements (Ti, Zr, V and Hf) of the Ti-Zr-V-Hf NEG films after heating, suggesting that the NEG films can be activated after heating and used as getter pumps.

Robots are very essential for modern nuclear power plants to monitor equipment conditions and eliminate accidents, allowing one to reduce the radiations on personnel. As a novel robot, a soft robot with the advantages of more degrees of freedom and abilities of continuously bending and twisting has been proposed and developed for applications in nuclear power industry. Considering the radiation and high-temperature environment, the overall performance improvement of the flexible materials used in the soft nuclear robot, such as the tensile property and gamma-ray shielding property, is an important issue, which should be paid attention. Here, a flexible gamma-ray shielding material silicone-W-based composites were initially doped with nano titanium oxide and prepared, with the composition of 20 silicone-(80-x) W-(x) TiO₂, where x varied from 0.1 to 2.0 wt.%. Structural investigations on SEM and EDS were performed to confirm the structure of the prepared composites and prove that all the chemicals were included in the compositions. Moreover, the tensile property of the composites at 25, 100, and 150 °C were investigated to study the effect of working temperature on the flexibility of the compositions. The attenuation characteristics including the linear attenuation coefficients and mass attenuation coefficients of the prepared silicone-W or silicone-W-TiO₂-based composites with respect to gamma ray were investigated. The stability of the silicone–tungsten-TiO₂-based composite at high temperature was studied for the first time. In addition, the influence of nano TiO₂ additive on the property’s variation of silicone-W-based composites was initially studied. The comparison of the properties such as the tensile elongation, thermal stability, and gamma-ray shielding of the synthesized silicone-W and silicone-W-TiO₂ composites showed that the addition of nano TiO₂ powders could be useful to develop novel gamma-ray-shielding materials for radiation protection of soft robots or other applications for which soft gamma-ray-shielding materials are needed.

The laser processing molybdenum metal surface method was first proposed to enhance the efficiency of multistage depressed collectors (MDCs). In this study, the secondary electron yield (SEY), surface geometrical morphologies and chemical states of laser processed Mo metal samples were characterized. For the first time, the effects of laser parameters and incident angle of primary electrons on the SEY property of laser induced nano and micro structures of molybdenum surface were investigated. The influence rule of laser processing patterns, power, pitch spacing, scanning speed on surface morphologies and SEY were systematically explored. A maximum SEY of laser processed Mo metal less than one was achieved. The Mo 3d and O 1s core level spectra of Mo metal before and after laser processing were analyzed in this study. Furthermore, the corresponding oxidation states of Mo as well as the relative distribution were elucidated.

The laser processing method has proven to produce surfaces while ensuring a low secondary electron yield of oxygen-free high-conductivity copper (OFHC) samples, making it attractive for electron cloud mitigation in next-generation particle accelerators and neutron tubes. In this work, the laser processing method is proposed to OFHC targets for the first time, aiming to reduce the secondary electrons in the neutron tube. The secondary electron yields (SEYs) and the thermal conductivities of Ti film and quaternary Ti–Zr–V–Hf films with unprocessed and laser processed OFHC substrates are investigated. Our results highlight that the thermal conductivity of Ti film with laser processed OFHC substrates is in proximity to the cleaned bare OFHC sample, especially at high temperatures. Moreover, the SEY of coated OFHC substrates are higher than that of coated laser processed substrates, which indicates the better secondary electron suppression capability of coated laser processed substrates. Therefore, the thermal conductivity and SEY results illustrate that the application of Ti and Ti–Zr–V–Hf coated laser processed OFHC can be considered to improve the neutron yield in neutron tubes in the future.

For improving the vacuum and mitigating the electron clouds in ultra-high vacuum chamber systems of high-energy accelerators, the deposition of Ti-V-Hf-Zr getter film on a laser-treated aluminum alloy substrate was proposed and exploited for the first time in this study. The laser-treated aluminum surface exhibits a low secondary electron yield (SEY), which is even lower than 1 for some selected laser parameters. Non-evaporable getter (NEG) Ti-V-Hf-Zr film coatings were prepared using the direct current (DC) sputtering method. The surface morphology, surface roughness and composition of Ti-V-Hf-Zr getter films were characterized and analyzed. The maximum SEY of unactivated Ti-V-Hf-Zr getter film on laser-treated aluminum alloy substrates ranged from 1.10 to 1.48. The X-ray photoelectron spectroscopy (XPS) spectra demonstrate that the Ti-V-Hf-Zr coated laser-treated aluminum alloy could be partially activated after being heated at 100 and 150 °C, respectively, for 1 h in a vacuum and also used as a pump. The results were demonstrated initially and the potential application should be considered in future particle accelerators.