Space Charge Accumulation and Decay in Dielectric Materials with Dual Discrete Traps

Zhaoliang Xing; Chong Zhang; Haozhe Cui; Yali Hai; Qingzhou Wu; Daomin Min

doi:10.3390/app9204253

Space Charge Accumulation and Decay in Dielectric Materials with Dual Discrete Traps

Applied Sciences ◽

10.3390/app9204253 ◽

2019 ◽

Vol 9 (20) ◽

pp. 4253 ◽

Cited By ~ 1

Author(s):

Zhaoliang Xing ◽

Chong Zhang ◽

Haozhe Cui ◽

Yali Hai ◽

Qingzhou Wu ◽

...

Keyword(s):

Space Charge ◽

Analytical Solutions ◽

Charge Injection ◽

Charge Trapping ◽

Dielectric Materials ◽

Dynamic Processes ◽

Charge Accumulation ◽

Charge Densities ◽

Short Period ◽

Trapped Charge

Charge trapping and de-trapping properties can affect space charge accumulation and electric field distortion behavior in polymers. Dielectric materials may contain different types of traps with different energy distributions, and it is of interest to investigate the charge trapping/de-trapping dynamic processes in dielectric materials containing multiple discrete trap centers. In the present work, we analyze the charge trapping/de-trapping dynamics in materials with two discrete traps in two cases where charges are injected continuously or only for a very short period. The time dependent trapped charge densities are obtained by the integration of parts in the case of continuous charge injection. In the case of instantaneous charge injection, we simplify the charge trapping/de-trapping equations and obtain the analytical solutions of trapped charge densities, quasi-free charge density, and effective carrier mobility. The analytical solutions are in good agreement with the numerical results. Then, the space charge dynamics in dielectric materials with two discrete trapping centers are studied by the bipolar charge transport (BCT) model, consisting of charge injection, charge migration, charge trapping, de-trapping, and recombination processes. The BCT outputs show the time evolution of spatial distributions of space charge densities. Moreover, we also achieve the charge densities at the same position in the sample as a function of time by the BCT model. It is found that the DC poling duration can affect the energy distribution of accumulated space charges. In addition, it is found that the coupling dynamic processes will establish a dynamic equilibrium rather than a thermodynamic equilibrium in the dielectric materials.

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Enhanced Insulation Performances of Crosslinked Polyethylene Modified by Chemically Grafting Chloroacetic Acid Allyl Ester

Polymers ◽

10.3390/polym11040592 ◽

2019 ◽

Vol 11 (4) ◽

pp. 592 ◽

Cited By ~ 3

Author(s):

Xin-Dong Zhao ◽

Wei-Feng Sun ◽

Hong Zhao

Keyword(s):

Space Charge ◽

Dielectric Breakdown ◽

Breakdown Strength ◽

Chloroacetic Acid ◽

Dielectric Materials ◽

Electrical Insulation ◽

Polar Group ◽

Charge Accumulation ◽

Allyl Ester ◽

Electrical Insulation Properties

Modified crosslinked polyethylene (XLPE) with appreciably enhanced DC electrical insulation properties has been developed by chemical modification of grafting chloroacetic acid allyl ester (CAAE), exploring the trapping mechanism of charge transport inhibition. The bound state traps deriving from grafted molecule are analyzed by first-principles calculations, in combination with the electrical DC conductivity and dielectric breakdown strength experiments to study the underlying mechanism of improving the electrical insulation properties. In contrast to pure XLPE, the XLPE-graft-CAAE represents significantly suppressed space charge accumulation, increased breakdown strength, and reduced conductivity. The substantial deep traps are generated in XLPE-graft-CAAE molecules by polar group of grafted CAAE and accordingly decrease charge mobility and raise charge injection barrier, consequently suppressing space charge accumulation and charge carrier transport. The well agreement of experiments and quantum mechanics calculations suggests a prospective material modification strategy for achieving high-voltage polymer dielectric materials without nanotechnology difficulties as for nanodielectrics.

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Effect of trapped charge accumulation on the retention of charge trapping memory

Journal of Semiconductors ◽

10.1088/1674-4926/31/12/124016 ◽

2010 ◽

Vol 31 (12) ◽

pp. 124016 ◽

Cited By ~ 1

Author(s):

Rui Jin ◽

Xiaoyan Liu ◽

Gang Du ◽

Jinfeng Kang ◽

Ruqi Han

Keyword(s):

Charge Trapping ◽

Charge Accumulation ◽

Charge Trapping Memory ◽

Trapped Charge

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Studies on Space Charge Accumulation Properties in Dielectric Materials

2019 2nd International Conference on Electrical Materials and Power Equipment (ICEMPE) ◽

10.1109/icempe.2019.8727258 ◽

2019 ◽

Cited By ~ 1

Author(s):

Tatsuo Takada

Keyword(s):

Space Charge ◽

Dielectric Materials ◽

Charge Accumulation

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Influence of Temperature on Charge Accumulation in Low-Density Polyethylene Based on Depolarization Current and Space Charge Decay

Polymers ◽

10.3390/polym11040587 ◽

2019 ◽

Vol 11 (4) ◽

pp. 587 ◽

Cited By ~ 5

Author(s):

Guochang Li ◽

Jiaxing Wang ◽

Wang Han ◽

Yanhui Wei ◽

Shengtao Li

Keyword(s):

Space Charge ◽

Charge Trapping ◽

Low Density Polyethylene ◽

Low Density ◽

Insulation Material ◽

Charge Accumulation ◽

Depolarization Current ◽

Close Link ◽

Influence Of Temperature ◽

Influence Of Temperature On

Temperature is one of the key factors affecting space charge accumulation in high voltage direct current (HVDC) cable insulation material. The influence of temperature on charge accumulation in low density polyethylene (LDPE) has been investigated with a combined thermally stimulated depolarization current (TSDC) method and pulsed electro-acoustic (PEA) method. The experimental results indicate that there exists a transition temperature region of charge accumulation around 50 °C. The total accumulated charges all firstly increase and then decrease with the increasing polarization temperature under three typical polarization electric fields, and they have more accumulated charges in LDPE around 50 °C. The phenomenon has a close link with the dynamic processes of charge trapping and de-trapping, which were verified by TSDC results. At room temperature, the trapped charges are difficult to release from the traps, and these homocharges near the cathode can depress the further injection of the charges. More charges can be injected from the electrodes with the increase of temperature, while the charge migration is relatively lower before 50 °C, leading to more accumulated charges. When the temperature exceeds around 50 °C, the molecular movement is accelerated which can enhance the hopping probability of charges between the adjacent traps, resulting in few accumulated charges.

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Space Charge Accumulation at Material Interfaces in HVDC Cable Insulation Part I—Experimental Study and Charge Injection Hypothesis

Energies ◽

10.3390/en13082005 ◽

2020 ◽

Vol 13 (8) ◽

pp. 2005

Author(s):

Espen Doedens ◽

E. Markus Jarvid ◽

Raphaël Guffond ◽

Yuriy V. Serdyuk

Keyword(s):

Field Strength ◽

Space Charge ◽

Transport Model ◽

Rough Surfaces ◽

Charge Injection ◽

Field Enhancement ◽

Life Time ◽

Charge Accumulation ◽

Material Interfaces ◽

Cable Insulation

On-site installation of accessories on extruded polymeric high voltage cables in a common practice. The procedure requires the shaping of the physical interface between the cable insulation surface and the pre-molded accessory body. On such interfaces, rough surfaces should be avoided in order to limit space charge accumulation in the insulation, which affects the cable performance by reducing insulation life-time, creating conditions for local field enhancement, and, respectively, the formation of possible breakdown path e.g. by electrical treeing. Space charge measurements on cable insulation peelings were undertaken to assess the space charge injection and accumulation on interfaces with varying degrees of surface roughness in order to improve understanding on this subject. The results of the measurements confirm the hypothesis regarding the enhancement of charge injection from rough surfaces when electric field strength exceeds a certain level. The accumulated charge density in the material is shown to strongly depend on the field strength and temperature in both polarization and subsequent depolarization measurements. These results emphasize that a bipolar charge transport model that incorporates field and temperature dependencies of charge injection, trapping, detrapping, and recombination processes needs to be adopted to accurately describe the observed electric conduction phenomena.

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Space Charge Accumulation at Material Interfaces in HVDC Cable Insulation Part II—Simulations of Charge Transport

Energies ◽

10.3390/en13071750 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1750

Author(s):

Espen Doedens ◽

E. Markus Jarvid ◽

Raphaël Guffond ◽

Yuriy V. Serdyuk

Keyword(s):

Surface Roughness ◽

Space Charge ◽

Charge Transport ◽

Transport Model ◽

Charge Injection ◽

Charge Trapping ◽

Material Interfaces ◽

Cable Insulation ◽

High Voltage Direct Current ◽

Cable Systems

Extruded high voltage direct current (HVDC) cable systems contain interfaces with poorly understood microscopic properties, particularly surface roughness. Modelling the effect of roughness on conduction in cable insulation is challenging, as the available results of macroscopic measurements give little information about microscopic charge distributions at material interfaces. In this work, macroscopic charge injection from interfaces is assessed by using a bipolar charge transport model, which is validated against a series of space charge measurements on cable peelings with different degrees of surface roughness. The electric field-dependent conduction and charge trapping effects stimulated by the injection current originating from rough surfaces are assessed. It is shown that by accounting for roughness enhanced charge injection with the parameters derived in part I of the paper, reasonable agreement between computed and measured results can be achieved at medium field strengths (10–40 kV/mm).

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Thermal Annealing of Radiation-Induced Trapped Charge in Simox and Thermal Oxide Thin Films

MRS Proceedings ◽

10.1557/proc-284-287 ◽

1992 ◽

Vol 284 ◽

Cited By ~ 2

Author(s):

D. Herve ◽

Ph. Paillet ◽

J. L. Leray

Keyword(s):

Thermal Annealing ◽

Low Dose ◽

Charge Trapping ◽

High Dose ◽

X Ray ◽

Charge Densities ◽

Large Bulk ◽

Thermal Oxide ◽

Radiation Induced ◽

Trapped Charge

ABSTRACTThe results of charge trapping and thermal annealing in X-ray irradiated SiO2 are presented. A comparative study is made between thermal oxide and SIMOX buried oxide behavior. At low dose (10 krad(SiO2)), X-ray induced charge trapping is found to be very different in thermal and SIMOX oxides. Results are interpreted in terms of a relatively large bulk trapping in SIMOX whereas thermal oxide behavior is dominatedby interface trapping. However, at high dose, both oxides behave similarly and are dominated by interface trapping. Etch-back experiments performed on SIMOX irradiated at 10krad (SiO2) and 1 Mrad (SiO2) reveal these two trapping regimes. Isochronal annealings have been performed up to 300°C on irradiated samples. Recovery data are interpreted assuming an energy distribution of trapped charge densities. Detrapping energies located at about 1.05 eV and 1.35 eV have been obtained in SIMOX whereas the thermal oxide exhibits a unique peak at 1.35 eV. Based on these data, SIMOX and thermal oxides are demonstrated to differ significantly.

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