Search results for "Space charge"

showing 10 items of 97 documents

Effect of space charge on the negative oxygen flux during reactive sputtering

2017

Negative ions often play a distinctive role in the phase formation during reactive sputter deposition. The path of these high energetic ions is often assumed to be straight. In this paper, it is shown that in the context of reactive magnetron sputtering space charge effects are decisive for the energetic negative ion trajectories. To investigate the effect of space charge spreading, reactive magnetron sputter experiments were performed in compound mode with target materials that are expected to have a high secondary ion emission yield (MgO and CeO2). By the combination of energy flux measurements, and simulations, a quantitative value for the negative oxygen ion yield can be derived.

010302 applied physicsAcoustics and UltrasonicsChemistryEnergy fluxContext (language use)02 engineering and technologySputter deposition021001 nanoscience & nanotechnologyCondensed Matter Physics01 natural sciencesSpace chargeMolecular physicsSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsIonCondensed Matter::Materials SciencePhysics::Plasma PhysicsSputteringYield (chemistry)0103 physical sciencesOxygen fluxAtomic physics0210 nano-technologyJournal of Physics D: Applied Physics
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Partial discharges behavior under different rectified waveforms

2017

In this work, a previous software used to simulate partial discharges (PDs) under Alternating Current (AC) stress has been modified in order to evaluate the PDs behavior under a voltage stress close to the Direct Current (DC) waveform. By using a full-wave and a half-wave rectifier, the specimen with an air void defects has been subjected to a gradual constant stress. Finally, a capacitive filter has been inserted in order to produce a steadier voltage supply. Simulation results show that under an almost DC waveform, the PDs activity become less compared to AC stress.

010302 applied physicsDC stressMaterials scienceHVDCPD modelbusiness.industryAcousticsCapacitive sensingDirect currentElectrical engineeringRectified waveform01 natural sciencesSpace charge010305 fluids & plasmaslaw.inventionStress (mechanics)RectifierSettore ING-IND/31 - Elettrotecnicalaw0103 physical sciencesWaveformPartial DischargebusinessAlternating currentVoltage
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Review of space charge measurement systems: acoustic, thermal and optical methods

2016

In the last decade, remarkable developments have concerned the methods of space charge measurement in the field of insulation systems diagnostic. In particular, methods based on acoustic and thermal phenomena have been largely used. The present review provides a broad overview on the different techniques used describing, for each of them, the working principle, the main features and the most relevant applications. Further details are provided for the Pulsed Electro-Acoustic (PEA) method, as it seems to be the most used. This article provides more details on its historical evolution, showing evidence for its technological limits and taking into consideration the advantages and drawn from the…

010302 applied physicsEngineeringField (physics)business.industry020209 energySystem of measurementMechanical engineering02 engineering and technology01 natural sciencesSpace chargeSettore ING-IND/31 - ElettrotecnicaSpace charge Charge measurement Acoustics Optical variables measurement Electrodes Acoustic measurements Optical pulses0103 physical sciencesThermal0202 electrical engineering electronic engineering information engineeringElectrical and Electronic EngineeringbusinessThermal methodsIEEE Transactions on Dielectrics and Electrical Insulation
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Space charge behavior of different insulating materials employed in AC and DC cable systems

2017

In this work, the space charge accumulation in three different XLPE based material has been carried out by using the PEA (Pulsed Electro-Acoustic) method. The specimens provided by a cables industry have been subjected to the same DC stress during polarization time at environment temperature. Afterwards, the high voltage generator has been turned off and the amount residual charge has been evaluated. The space charge profiles during polarization and depolarization have been carried out and compared. Finally, the distribution of electric field within the samples has been reported. In particular, the maximum distortion of electric field has been calculated by taking into account the distribut…

010302 applied physicsHvdcMaterials scienceCondensed matter physics020209 energyDepolarizationHigh voltage02 engineering and technologyDC stre01 natural sciencesSpace chargeSpace chargeElectronic Optical and Magnetic MaterialsSettore ING-IND/33 - Sistemi Elettrici Per L'EnergiaSettore ING-IND/31 - ElettrotecnicaPea methodElectric field0103 physical sciencesResidual charge0202 electrical engineering electronic engineering information engineeringAdditiveElectrical and Electronic EngineeringPolarization (electrochemistry)2017 International Symposium on Electrical Insulating Materials (ISEIM)
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Space charge accumulation in undersea HVDC cables as function of heat exchange conditions at the boundaries – water-air interface

2020

Transmission lines with undersea HVDC cables are an interesting technological solution for the supply of electrical energy to islands. The accumulation of space charge inside the dielectric layer of a HVDC cable is one of the most important element to consider in its design and during operation. The formation of space charge is due to various factors including the high dependence on the temperature of the electrical conductivity of the insulation and the establishment of a thermal gradient under load conditions. This research is focused on the space charge accumulation phenomenon around a section of a HVDC cable half dipped in water and half in air. Due to the high difference in thermal con…

010302 applied physicsMaterials science020209 energyElectric potential energy02 engineering and technologyMechanicsThermal conduction01 natural sciencesSpace chargeHVDC cables space charge sustainable islandsSettore ING-IND/31 - ElettrotecnicaTemperature gradientThermal conductivityElectric power transmissionElectric field0103 physical sciencesHeat exchanger0202 electrical engineering electronic engineering information engineering2020 IEEE 20th Mediterranean Electrotechnical Conference ( MELECON)
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Contributed Review: Review of thermal methods for space charge measurement.

2016

The space charge accumulation phenomenon has garnered great interest over the last two decades because of the increased use of direct current in high voltage electrical systems. In this context, a significant relevance has been achieved by the thermal methods, used for solid dielectrics. This paper presents a review of this non-destructive measurement system used for the measurement of space charge. The thermal pulse method, the thermal step method, and the laser intensity modulation method are described. For each configuration, the principle of operation, the thicknesses analyzed, and the spatial resolution are described, reporting also the main related applications

010302 applied physicsMaterials science020209 energySystem of measurementDirect currentContext (language use)High voltage02 engineering and technologySettore ING-IND/32 - Convertitori Macchine E Azionamenti Elettrici01 natural sciencesEngineering physicsSpace chargeSettore ING-IND/33 - Sistemi Elettrici Per L'EnergiaSettore ING-IND/31 - ElettrotecnicaModulation0103 physical sciencesThermal0202 electrical engineering electronic engineering information engineeringInstrumentationIntensity modulationthermal methods space charge measurementThe Review of scientific instruments
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Space Charge Measurement under DC and DC Periodic Waveform

2018

In High Voltage systems, Partial Discharges (PDs) monitoring are one of the main diagnostic instrument to evaluate the reliability of the apparatus. Under Alternating Current (AC) stress, PDs detection and recognition techniques are well consolidated. On the contrary, the monitoring of PDs under Direct Current (DC) stress is difficult due to complexities related to the nature of the phenomenon, which cause the beginning of PDs events in proximity of the dielectric breakdown. This problem has been partially overcome by using a continuous Periodic waveform (DCP) with positive average value, as described in a recent published work. Under DC stress, another degradation factor is the Space Charg…

010302 applied physicsMaterials scienceDielectric strengthPEA methodElectronic Optical and Magnetic MaterialDirect currentHigh voltageDC stre01 natural sciencesSpace chargeSpace chargelaw.inventionComputational physicsStress (mechanics)Settore ING-IND/31 - ElettrotecnicaDCP strelawDCP waveform0103 physical sciencesWaveformElectrical and Electronic Engineering010306 general physicsAlternating currentVoltage
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Space Charges and Partial Discharges Simultaneous Measurements under DC Stress

2016

In the field of HVDC, the main causes of insulation aging are due to the space charge and PD phenomena. In particular, the purpose of the present work is to verify a possibility to measure simultaneously the space charge and the PDs under DC stress in order to evaluate the correlation between both phenomena. The space charge was measured by using a modified PEA cell and PDs were measured by using a novel wireless sensor system. The space charge profile and the PD pulses carried out simultaneously have been reported and discussed.

010302 applied physicsMaterials sciencebusiness.industry020209 energyElectrical engineering02 engineering and technologyMechanicsSpace (mathematics)01 natural sciencesspace charge partial discharges DC stress HVDCStress (mechanics)Settore ING-IND/31 - Elettrotecnica0103 physical sciences0202 electrical engineering electronic engineering information engineeringbusiness
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Deformation of bubbles in silicon gel insulation under an alternating electric field

2019

The behavior of silicone gel under electrical stress plays a significant role in the reliability and durability of high voltage electronic power devices due to its widespread use for the insulation of IGBT modules and other components. The charges accumulation at the bubble boundaries leads to significant displacements due to the establishment of Coulombic forces and the high deformability of colloidal system. The main purpose of this work is to validate a numerical approach useful to investigate, for a given silicone gel, the non-linear relation between the applied HVDC stress and the electric field over an air bubble within the insulation bulk. The analysis has been carried out by means o…

010302 applied physicsMaterials scienceinsulationreliabilityDeformation (mechanics)020209 energyBubbleHigh voltage02 engineering and technologyDielectric01 natural sciencesSpace chargeIGBTSilicone gelStress (mechanics)chemistry.chemical_compoundpartial dischargeSettore ING-IND/31 - ElettrotecnicaSiliconechemistryElectric field0103 physical sciences0202 electrical engineering electronic engineering information engineeringComposite material
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Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens

2021

Review of scientific instruments 92(5), 053703 (2021). doi:10.1063/5.0046567

010302 applied physicsPhotonMaterials scienceElectronPhotoelectric effect01 natural sciencesFluenceSpace charge010305 fluids & plasmas620Electric fieldExtreme ultraviolet0103 physical sciencesddc:620Atomic physicsInstrumentationStorage ring
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