Laser Annealing Effects on DC Surface Flashover of PMMA and Polystyrene

Zirnheld, J.; Olabisi, S.; Strzempka, P.; Burke, K.; Ali, Y.S.; Belkind, A.; Tompa, Gary S.

doi:10.1109/ipmc.2008.4743635

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…In addition to filling inorganic particles, a few studies also devote to proposing different methods to modify the segment chemical structure or the main chain spatial conformation of the polymer matrix itself, thus directly changing the trapping characteristics of polymer materials. − Zirnheld et al study the effects of laser annealing on the DC flashover voltage of polymethyl methacrylate (PMMA) and polystyrene (PS). Li et al modify the trapping characteristics of cross-linked polyethylene (XLPE) by changing its crystallinity and grain size through annealing the samples with different cooling temperature profiles, achieving an enhancement of vacuum flashover performance comparable to nanocomposites, while avoiding introducing too many defects caused by poor structural compatibility.…”

Section: Introductionmentioning

confidence: 99%

Excellent Vacuum Pulsed Flashover Characteristics Achieved in Dielectric Insulators Functionalized by Electronegative Halogen–Phenyl and Naphthyl Groups

et al. 2022

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Designing electrical insulation materials with excellent surface flashover strength in a vacuum environment is crucial for highpower equipment and aerospace devices. In the present paper, the effect of two types of electronegative groups, the halogen−phenyl groups and the aromatic π-conjugated naphthyl groups, is used to greatly improve the vacuum flashover characteristics of polystyrene (PS), a commonly used polymer dielectric material in high-power devices. By polymerization of the monomers containing these electronegative groups, the bulk insulation material as a whole is modified expediently. In comparison to the base polymer PS, the electron affinity of the structures containing strong electronegative groups is studied with first-principles calculations based on the density functional theory. The nanosecond pulsed vacuum flashover testing results show that the vacuum flashover strength is increased by 10% after replacing the PS pendant phenyl groups with fluorophenyl groups and increased by 44% when replaced with the naphthyl groups. Furthermore, the thermally stimulated current and secondary electron emission yield spectroscopies are measured, to study the influence of strong electronegative groups on the trapping characteristics and further the electron-emitting features of the polymer dielectrics, which are closely related to the charged particle multiplication process during the vacuum flashover. The results prove that introducing strong electronegative groups can inhibit the triggering of vacuum flashover, suppress the electron emission, delay the flashover process, and thus greatly increase the vacuum flashover voltage. The study of this paper not only puts forward two groups of easily processable polymers with excellent vacuum flashover strength but also paves ways for the future material design of special insulation polymers.

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Section: Introductionmentioning

confidence: 99%

Excellent Vacuum Pulsed Flashover Characteristics Achieved in Dielectric Insulators Functionalized by Electronegative Halogen–Phenyl and Naphthyl Groups

et al. 2022

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“…Therefore, suppressing the charge emission and enhancing the charge absorption to prevent the charge multiplication and accumulation are critical to enhancing the flashover resistance of dielectrics. To suppress the electron emission of polymeric materials, on the one hand, many material modification methods have been proposed to physically modify the surface morphology, including specific thermal treatments, dielectric barrier discharge treatment, , laser annealing, , and electron beam irradiation . These modifications are indeed effective, while they all share the flaw that the effect is unstable and not lasting.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Surface Flashover Strength of Polystyrene in Vacuum by Secondary Electron Emission Suppression through Cross-Linking

et al. 2021

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Insulation materials with excellent dielectrics−vacuum interface breakdown strength are irreplaceable in equipment such as particle accelerators, fusion ignition, and related aerospace devices. In this article, the segment structure of a typical insulation polymer, polystyrene, has been modified by introducing divinylbenzene to form cross-linking junctures and adjust the cross-linking density. The influence of cross-linking on its electron absorb-emit feature and further on the vacuum pulsed flashover characteristics has been systematically studied. A series of broadband dielectric spectroscopy (BDS) and thermally stimulated current (TSC) experiments indicate that this cross-linking network inhibits the movement of the polar segments, leading to a drastic change in the charge-trapping behavior of dielectric surface layer materials. The trapping charge density is increased, and the trapping energy is transferred to deeper-level regions. These lead to the observed suppression of secondary electron emission (SEE) of highly cross-linked polystyrenes exposed in vacuum. And, quite sensibly, the nanosecond pulsed vacuum flashover tests show that the polystyrenes with higher crosslinking density have enhanced flashover strength. Moreover, to further investigate the relationship between the dielectric SEE behavior and its vacuum flashover process, a 2-D model is established and analyzed on the basis of the particle in the cell with the Monte Carlo collision (PIC-MCC) method.

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