Space Charge Modulated Electrical Breakdown

Abstract

Electrical breakdown is one of the most important physical phenomena in electrical and electronic engineering. Since the early 20th century, many theories and models of electrical breakdown have been proposed, but the origin of one key issue, that the explanation for dc breakdown strength being twice or higher than ac breakdown strength in insulating materials, remains unclear. Here, by employing a bipolar charge transport model, we investigate the space charge dynamics in both dc and ac breakdown processes. We demonstrate the differences in charge accumulations under both dc and ac stresses and estimate the breakdown strength, which is modulated by the electric field distortion induced by space charge. It is concluded that dc breakdown initializes in the bulk whereas ac breakdown initializes in the vicinity of the sample-electrode interface. Compared with dc breakdown, the lower breakdown strength under ac stress and the decreasing breakdown strength with an increase in applied frequency, are both attributed to the electric field distortion induced by space charges located in the vicinity of the electrodes.

Deformation-induced charge redistribution in ceria thin film at room temperature

“…This diamond structure is also observed in STEM-BF and STEM-high angle annular dark field (STEM-HAADF) images near the indent on the CeO 2 thin film (Figures 4k, S12a, and S12c) and undistorted CeO 2 thin film (far removed from the indent), as shown in Figure S13 Figure S12). This difference is thought to arise from the broken symmetry of O ions (including the contrast coming from vacuum transmission) by the movement of O ions in the T-CeO 2 phase (as illustrated in (2-3) to (2)(3)(4)(5) in Figure S12). This zigzag pattern observed along the diagonal direction has never been observed from the cubic structure of CeO 2 , and we could not observe this peculiar contrast in the undistorted region of the CeO 2 thin film ( Figure S13).…”

“…Region a is the CeO 2 structure maintaining the initial cubic structure even though the thin film experiences plastic deformation upon indentation ( Figure S12a). Ce ions in the CeO 2 phase ( Figure S12a) exhibit diamond structures (blue solid lines serve as a guide; illustrated in Figures (1-1) and (1)(2) in Figure S12). The yellow, green, and orange circles in Figure (1-2) are superimposed on Figure S12a in order to show that the material in the STEM images in Figure S12a has the same structure as pristine CeO 2 .…”

“…The fact that electronic characteristics of space charge layers differ from bulk phases [1,2] is considered the key factor in tuning various properties of photocatalysts [3], gas sensors [4][5][6], batteries [7][8][9], and solid-state fuel cells (or ion conductors) [10,11]. For example, gas sensors generally sense current change, the magnitude of which varies depending on the extent of band bending caused by formation of the space charge layer [12,13] during electrochemical equilibration between the adsorbate and the sensing surface.…”

DC Model Cable under Polarity Inversion and Thermal Gradient: Build-Up of Design-Related Space Charge

“…Such models have been set up mostly for flat specimen, but extension and resolution in cable geometry is appearing [36]. Also, it was used as a route to model breakdown under DC stress [37]. Although this is a promising route to develop accurate modelling of insulations, at present the full parameterization is still demanding; also the treatment of physical processes like ionization and heterocharge build-up is still in the infancy stage [38].…”

Space charge characteristics of fluorinated polyethylene: Different effects of fluorine and oxygen

“…[1][2][3] Many researchers conducted efforts on the mechanism and suppression of space charge by both bulk 4,5 and interface modifications, 6 such as micro-or nano-particle doping and plasma process, etc. Direct fluorination has been proved to be an effective interface process method, suppressing space charge distribution in polymer.…”