A time-resolved current method and TSC under vacuum conditions of SEM: Trapping and detrapping processes in thermal aged XLPE insulation cables

Boukezzi, Larbi; Rondot, S.; Jbara, O.; Boubakeur, A.

doi:10.1016/j.nimb.2017.01.011

Cited by 8 publications

(6 citation statements)

References 30 publications

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“…At room temperature and at 50 °C, no detrapped charges occurred because of the relatively low applied temperature, so the resulting influence current maintains its null values. It has been evidenced in previous papers that XLPE has a strong ability to store charges at room temperature after stopping e-beam irradiation [ 17 , 23 ]. When the applied temperatures rise (80 °C and 90 °C), we notice an abrupt change of sign in the influence current that becomes positive.…”

Section: Resultsmentioning

confidence: 99%

“…In Figure 3 b, we have presented the charging process giving the evolution of influence current during all the periods where the e-beam irradiation is on for each test temperature alone. The discharging process is given in Figure 3 c. From this exploded form, it is clear that at room temperature, the influence current takes the usual form [ 17 ]. It starts its evolution from a maximum (in absolute value) negative value and decays rapidly to reach zero after a few hundred seconds.…”

Section: Resultsmentioning

confidence: 99%

“…Many scholars have applied only isothermal conditions under DC stress to study the temperature’s effect on the charging process (trapped charges) [ 14 , 15 ], and others [ 16 ] have applied isothermal conditions under charging process to evaluate the trapped charge dependence on the applied temperature and non-isothermal conditions to evaluate the detrapping charges. In another work, presented in [ 17 ], only the non-isothermal treatment has been applied to stimulate the material to release the trapped charges under electron beam irradiation. Furthermore, the temperature gradient effect on the space charges distribution through the thickness of the insulation has been analyzed in [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Isothermal Conditions on the Charge Trapping/Detrapping Parameters in e-Beam Irradiated Thermally Aged XLPE Insulation in SEM

et al. 2022

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The effect of isothermal conditions on the trapping/detrapping process of charges in e-beam irradiated thermally aged XLPE insulation in scanning electron microscopy (SEM) has been investigated. Different isothermal conditions ranging from room temperature to 120 °C are applied on both unaged and aged XLPE samples (2 mm thick) by a suitable arrangement associated with SEM. For each applied test temperature, leakage, and influence currents have been measured simultaneously during and after e-beam irradiation. Experimental results show a big difference between the fresh and aged material regarding trapping and detrapping behavior. It has been pointed out that in the unaged material deep traps govern the process, whereas the shallow traps take part in the aged one. Almost all obtained results reveal that the trapped charge decreases and then increases as the temperature increases for the unaged sample. A deflection temperature corresponding to a minimum is observed at 50 °C. However, for the aged material, the maximum trapped charge decreases continuously with increasing temperature, and the material seems to trap fewer charges under e-beam irradiation at high temperature. Furthermore, thermal aging leads to the occurrence of detrapping process at high temperatures even under e-beam irradiation, which explains the decrease with time evolution of trapped charge during this period. The recorded leakage current increases with increasing temperature for both cases with pronounced values for aged material. The effect of temperature and thermal aging on electrostatic influence factor (K) and total secondary electron emission yield (σ) were also studied.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Isothermal Conditions on the Charge Trapping/Detrapping Parameters in e-Beam Irradiated Thermally Aged XLPE Insulation in SEM

et al. 2022

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“…The invariant conductivity is seen in samples aged such that CI > 0.4 is also consistent with such process, whereby an increase of the density of traps facilitates percolation processes. This effect of ageing at 120°C on the traps present in XLPE has been considered by Boukezzi et al [56], who estimated a resultant trap depth of 0.8–0.9 eV based upon their thermal stimulated current measurements.…”

Section: Ageing Morphology and Charge Transportmentioning

confidence: 91%

Ageing behaviour of a polyethylene blend: influence of chemical defects and morphology on charge transport

2020

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The properties of novel cable insulation systems will rely critically upon the morphology of the material. Here, a blend of high and low-density polyethylene (PE) was processed in order to generate three sets of samples with different morphologies. The influence of thermo-oxidative ageing at 120°C was then considered. The resulting chemical changes included the introduction of unsaturation and oxygen-containing groups and were determined by antioxidant consumption and oxygen permeability. Such chemical defects were found to be concentrated in the fraction of each system that was molten at 120°C and, consequently, served to inhibit recrystallisation following ageing. The resulting spatial distribution of charge trapping sites was therefore strongly dependent on morphology. The electrical conductivity of each system varied non-monotonically with ageing: short times reduced the conductivity; a rapid increase in conductivity over five orders of magnitude occurred beyond a critical ageing threshold. Despite the pronounced structural differences between the morphologically distinct sets of samples, all exhibited comparable conductivity values beyond this threshold, implying that while charge transport is strongly influenced by chemical factors, crystallinity is relatively unimportant. This experimental finding appears at odds with theoretical studies of the electronic states in crystalline and amorphous PE.

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“…Although the EaB for both EPR The inconsistent behavior of the S r values at 1 s as shown in Figure 12, with radiation, indicates a parallel occurrence of a cross-linking reaction during irradiation. As the crosslinking reaction results in a three-dimensional network within the molecules, it restricts charge transportation mobility [35]. This can decrease the polarization conductivity and thus the S r value.…”

Section: Cspe Jacketmentioning

confidence: 99%

Implementation of Non-Destructive Electrical Condition Monitoring Techniques on Low-Voltage Nuclear Cables: I. Irradiation Aging of EPR/CSPE Cables

et al. 2021

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In a nuclear power plant environment, low-voltage cables experience different stresses during their service life which challenge their integrity. A non-destructive and reliable condition monitoring technique is desired to determine the state of these low-voltage cables during service and for the life extension of nuclear power plants. Hence, in this research work, an EPR/CSPE-based low-voltage cable was exposed to γ-rays for five different absorbed doses. The overall behavior of the cable under stress was characterized by frequency and time domain electrical measurements (capacitance, tan δ, and Extended Voltage Response) and a mechanical measurement (elongation at break). Significant variations in the electrical parameters were observed, as was a decline in the elongation at break values. A strong correlation between the measurement methods was observed, showing the ability of the electrical methods to be adopted as a non-destructive condition monitoring technique.

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A time-resolved current method and TSC under vacuum conditions of SEM: Trapping and detrapping processes in thermal aged XLPE insulation cables

Cited by 8 publications

References 30 publications

Effect of Isothermal Conditions on the Charge Trapping/Detrapping Parameters in e-Beam Irradiated Thermally Aged XLPE Insulation in SEM

Effect of Isothermal Conditions on the Charge Trapping/Detrapping Parameters in e-Beam Irradiated Thermally Aged XLPE Insulation in SEM

Ageing behaviour of a polyethylene blend: influence of chemical defects and morphology on charge transport

Implementation of Non-Destructive Electrical Condition Monitoring Techniques on Low-Voltage Nuclear Cables: I. Irradiation Aging of EPR/CSPE Cables

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