Space charge behavior in LDPE with evaporated electrode under ultra-high electric field

Matsui, Kohei; Miyawaki, Atsushi; Tanaka, Yasuhiro; Takada, Tatsuo; Liu, R.; Maéno, Takashi

doi:10.1109/iseim.2005.193339

Cited by 1 publication

(1 citation statement)

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“…The formation and transportation mechanism of space charge has been the subject of extensive experimentation [2]. For example, by monitoring the threshold electric field for charge accumulation it has been found that charge injection is strongly affected by the material of the electrode [3][4][5]. Space charge formation and transport phenomena under DC stress can be observed using the Pulsed Electro-Acoustic (PEA) method [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Molecular modeling and electron transport in polyethylene

Wang

Cubero

et al. 2014

IEEE Trans. Dielect. Electr. Insul.

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Polyethylene is commonly used as an insulator for AC power cables. However it is known to undergo chemical and physical change which can lead to dielectric breakdown. Despite almost eighty years of experimental characterization of its electrical properties, very little is known about the details of the electrical behaviour of this material at the molecular level. An understanding of the mechanisms of charge trapping and transport could help in the development of materials with better insulating properties required for the next generation of high voltage AC and DC cables. Molecular simulation techniques provide a unique tool with which to study dielectric processes at the atomic and electronic level. Here we summarise simulation methodologies which have been used to study the properties of PE at the molecular level, elucidating the role of morphology in the trapping of excess electrons. We find that polyethylene has localised states due to conformational trapping extending below the mobility edge (above which the excess electrons are delocalised), at -0.1±0.1eV with respect to the vacuum level. These trap states with localisation lengths between 0.3 and 1.2nm have energies as low as -0.4±0.1eV in the amorphous and interfacial regions of polyethylene with more positive values in lamella structures. Crystalline regions have a mobility edge at +0.46 ±0.1eV, so we would expect transport by electrons excited above the mobility edge to delocalised states to be predominantly through amorphous regions if they percolate the sample.

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