Dielectric Properties of Cryogenic Liquids

Mathes, K. N.

doi:10.1109/tei.1967.298846

Cited by 65 publications

(9 citation statements)

References 13 publications

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“…This issue has lead to some inconsistencies in published results regarding the existence of a gap size effect for electrical breakdown in LHe. Several previous studies 28, [33][34][35][36][37] have shown that the breakdown voltage increases approximately linearly with gap size, whereas the results from others 38,39 have suggested a possible square-root law as found in vacuum breakdown. At the same time, it has also been suggested that whenever spherical electrodes are used, a hidden area effect could emerge.…”

Section: Scale Dependencementioning

confidence: 99%

A study of DC electrical breakdown in liquid helium through analysis of the empirical breakdown field distributions

Phan,

Wei,

Beaumont

et al. 2020

Preprint

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We report results from a study on electrical breakdown in liquid helium using near-uniform-field stainless steel electrodes with a stressed area of ∼0.725 cm 2 . The distribution of the breakdown field is obtained for temperatures between 1.7 K and 4.0 K, pressures between the saturated vapor pressure and 626 Torr, and with electrodes of different surface polishes. A data-based approach for determining the electrode-surfacearea scaling of the breakdown field is presented. The dependence of the breakdown probability on the field strength as extracted from the breakdown field distribution data is used to show that breakdown is a surface phenomenon closely correlated with Fowler-Nordheim field emission from asperities on the cathode. We show that the results from this analysis provides an explanation for the supposed electrode gap-size effect and also allows for a determination of the breakdown-field distribution for arbitrary shaped electrodes. Most importantly, the analysis method presented in this work can be extended to other noble liquids to explore the dependencies for electrical breakdown in those media.1 Ref. 7 reports measurements at 0.4 K

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Section: Scale Dependencementioning

confidence: 99%

A study of DC electrical breakdown in liquid helium through analysis of the empirical breakdown field distributions

Phan,

Wei,

Beaumont

et al. 2020

Preprint

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“…Helium and nitrogen, due to their inert nature, are the most widely used cryogenic liquids. Liquid nitrogen has a maximum breakdown strength of 1.6-1.9 MV/cm and dielectric constant of 1.431 [26][27][28][29][30]. Liquid hydrogen and liquid oxygens are commonly used for space applications as low-cost cryo-fuels.…”

Section: Cryogenic Cooling Systems For Mw-class Power Electronicsmentioning

confidence: 99%

Conceptual design of a wide band gap based cryogenically cooled MW-class inverter

Kar

Reddy

Rajashekara

2022

IOP Conf. Ser.: Mater. Sci. Eng.

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The increasing need for higher power density and closer integration of power subsystems consisting of superconducting motors/generators, degaussing coils, energy storage modules, and cables leads one to consider the merits of refrigerating the associated power electronics down to cryogenic temperatures. High temperature superconducting (HTS) components combined with cryogenic power converters resulting in high power density power conversion systems will have a significant effect on several industrial, commercial, transportation, and renewable energy applications. Cryogenic power converters provide promising benefits over their room temperature counterparts in terms of reduced size and weight due to increased power density, improved efficiency, switching speed, and reliability. Integration could result in significant weight and space savings for the overall system. In this paper, a conceptual design study on the wide-bandgap-based (especially SiC and GaN) MW-class power inverter/converter is reported. Based on the total power loss of the designed converter, different cryogenic cooling strategies are proposed. The cooling power requirements, cooler mass, the cooler cost is evaluated based on the operating temperature of MW-class power converter. Finally, a power density comparison for different types of conventional power applications and HTS applications together with MW-class power converters is presented. The future of the cryogenically cooled power electronics system together with superconducting power devices is described for large-scale applications such as for future electric aircraft.

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“…Former studies have thoroughly investigated the dielectric properties of cryogenic fluids, such as nitrogen (N2), helium (He) and hydrogen (H2) [5,6]. The permittivity, conductivity, dielectric loss and breakdown strength under different conditions are known [7].…”

Section: Potential Dielectrics For Cryogenic Interruptionmentioning

confidence: 99%