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In this paper, through the application of 3D printing technology, insulators with different surface microstructures are prepared. Surface flashover test of the printed insulators shows that surface microstructures have a strong influence on the surface flashover voltage. This indicates that through proper surface microstructure design and the application of 3D printing technology insulators with high surface voltage withstand strength can be prepared. The influence of gas release characteristics, with and without thermal treatment, on the surface flashover voltages is studied. The results indicate that insulators with lower gas release rate own higher voltage withstand strength.

Resistance to intense electron beam bombardment of TiC/Graphite was investigated numerically and experimentally. The results indicate that the decreasing of initial electron energy and the increasing of TiC coating thickness could both enhance the electron energy deposition inside the surface layer of the TiC/Graphite, and finally cause the increasement of the temperature differences at the interface between TiC coating and graphite substrate. The graphite substrate is well coated with TiC in all the TiC/graphite targets, and the morphology of the TiC coatings could be controlled by adjusting its thickness. Under electron beam with accelerating voltage of 850 keV, current of 11 kA, pulsewidth of 40 ns and pulse number of 30 times, TiC/Graphite target with TiC coating thickness of 1 μm shows more excellent electron beam bombardment resistance, agreeing with the results of the numerical modeling.

Molecule self-assembly on the surface of alumina ceramic and its influence on the surface flashover characteristics of the alumina ceramic insulators were studied in this paper. First, octadecyltrichlorosilane was assembled on the surface of alumina ceramic insulators in the toluene solution. Then, 393 K thermal treatment of 2 h was conducted on the specimens to promote the growth of the molecule membrane. Quality detection of the prepared molecule membrane by Energy Dispersive x-ray Analysis and water contact angle test showed that the molecules were linked to the alumina surface and the arrangement of the molecules on the surface was regular and tight. Gas release characteristic suggested that the formation of the molecule membrane made the gas release rate of the treated alumina decrease. The flashover voltage test on the home-made, short-pulsed, high-voltage vacuum platform indicated that the flashover voltages of the treated insulators increased by over 200% compared with the original alumina insulators. These results indicated that a layer of regular molecule membrane was formed on the surface of alumina through molecule self-assembly, which could improve the surface voltage withstand strength of the treated insulators.

The fabrication method of grooves on the surface of alumina and their influence on the surface flashover characteristics of the alumina insulator were studied in this paper. To prepare grooves with a regular surface structure, the UV laser was applied to carve grooves on the surface of alumina ceramic, and dilute hydrochloric acid was used to corrode and remove the residual materials produced in the laser carving process. By adjusting the laser parameters, periodic grooves were prepared on the surface of a cylindrical alumina insulator with a groove depth of 60 µm and a groove width of approximately 50 µm on the laser spinning carving platform. Then, alumina insulators with different periods were prepared, and their vacuum surface flashover voltages were tested on a short pulsed high-voltage test platform. The test results indicated that the flashover voltages of the alumina insulators with laser carved periodic grooves were increased over 200%, and the improvement did not change much with the groove periods. A further study of the groove parameters showed that several grooves fabricated on the cathode end of the insulators were able to improve the flashover voltage of the alumina insulator to the voltage-withstand level of the fully grooved insulators.

To investigate the electrochemical performance of MO (M=Co, Fe, Ni) nanostructures on lithium insertion and extraction, size-controlled LiF-MO nanocomposite thin-film electrodes, consisting of metallic M and M oxide (MO) nanoparticles in an amorphous, inert LiF matrix, were designed and fabricated using a RF sputtering system with metallic M and LiF mixture targets. The structural and electrochemical properties of nanocomposite thin-film electrodes were characterized using TEM, SAED, XRD, XPS, and electrochemical measurements. The results showed that MO particles with average particle sizes of ca.10nm were well-dispersed in LiF matrix to form a kind of homogeneous LiFMO nanocomposite by the sputtering method. The inert medium of LiF provides an effective matrix to prevent the crystallization and agglomeration of MO during the deposition and electrochemical cycling of the thin film electrode, and then the well-formed nanophase structure in the nanocomposite thin-film electrodes leads to an excellent electrochemical cycling performance with the stable discharge specific capacity above 300mAh/g.

Seeking an insulator supporting high voltage and short pulsed-power electric field in vacuum is an important topic especially for some sophisticated equipments. The voltage breakdown along the surface of insulator in vacuum (i.e. surface flashover) is one of the most serious problems for insulators, and it greatly limits the overall performance of a vacuum-dielectric system. The improvement of surface flashover characteristics of insulators in vacuum become a significant challenge for the development of high voltage pulsed-power devices. Herein, we report a simple and convenient avenue to achieve the high surface flashover performance of high density polyethylene (HDPE) in vacuum based on direct fluorination technique. The physicochemical properties of the fluorinated HDPE (i.e., surface morphology, the chemical component, structure and dielectric capability) were comparatively investigated with the untreated HDPE. The surface flashover characteristics of HDPE in vacuum were mainly discussed. The performance of HDPE at different fluorination temperature was also investigated. The results demonstrated that the direct fluorination strategy developed in this work is an effective means to improve the surface dielectric capability of insulators in vacuum. It is believed to provide a novel possibility for the common insulators applied in high electric field vacuum environments.

A composite micro-textured surface structure is proposed and demonstrated to enhance the surface flashover strength of polymer insulators used in vacuum. The structure is fabricated in two stages, with periodic triangular grooves of approximately 210 μm in width formed in the first stage and micro-holes of approximately 2 μm coated on the inner surface of grooves in the second. The aim is to exploit the synergistic effects between the grooves and micro-holes to suppress the secondary electron yield to obtain a better flashover performance. To acquire insulators with the composite micro-textured surface, the CO2 laser processing technique is applied to treat the surface of the PMMA insulators. The test results show that the flashover voltages of the insulators with the two-stage fabricated structure increase by 150% compared with the untreated samples in the best state. Compared with the traditional macro-groove structures on insulators, the proposed composite micro-textured insulators exhibit a better sur...