Surface charge measurement by the Pockels effect
Surface charge measurement by the Pockels effect
This thesis is concerned with the design and development of a surface charge measurement system using Pockels effect. The measurement of surface charge is important in determining the electrical performance of high voltage insulation materials. The method proposed allows on-line measurement of charge and can generate two-dimensional images that represent the charge behaviour on the surface of the material under test.
The measurement system is optical and uses a Pockels crystal as the sensing element. The Pockels cell uses a wafer of Bismuth Silicon Oxide (BSO). Surface charge creates an electric field within the Pockels crystal and induces anisotropy. A laser light is used to detect any change in anisotropy. This approach allows non-destructive measurements since no direct electric signal or component interferes with the surface charge. Furthermore, the optical measurement system can dynamically observe and simultaneously quantify surface charge which is not possible using conventional methods. This allows the surface charge distribution under the influence of a time varying electric field to be studied. The system's accuracy and sensitivity have been improved through the use of an Optical Phase Modulator. The system uses a high speed CCD camera with a maximum frame rate of 1000 frames per second and Synchronisation Control Circuit to obtain a high temporal resolution. This has allowed the study of charge behaviour at mains power frequencies.
Surface charge distributions have been observed by applying both impulse and AC voltages to a needle electrode in direct contact with the BSO. AC surface discharge behaviour of polymeric materials bonded to the BSO has also been investigated. The effect of the surrounding environment has been experimentally examined by placing the cell inside a vacuum chamber. Surface charge measurements have been made at various atmospheric pressures. The effect of an electro-negative gas (Sulphur Hexafluoride) on the surface charge distribution has also been investigated.
University of Southampton
Sam, Yao Long
f8798d2e-378d-4081-9cde-6dc2e2146999
2001
Sam, Yao Long
f8798d2e-378d-4081-9cde-6dc2e2146999
Sam, Yao Long
(2001)
Surface charge measurement by the Pockels effect.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis is concerned with the design and development of a surface charge measurement system using Pockels effect. The measurement of surface charge is important in determining the electrical performance of high voltage insulation materials. The method proposed allows on-line measurement of charge and can generate two-dimensional images that represent the charge behaviour on the surface of the material under test.
The measurement system is optical and uses a Pockels crystal as the sensing element. The Pockels cell uses a wafer of Bismuth Silicon Oxide (BSO). Surface charge creates an electric field within the Pockels crystal and induces anisotropy. A laser light is used to detect any change in anisotropy. This approach allows non-destructive measurements since no direct electric signal or component interferes with the surface charge. Furthermore, the optical measurement system can dynamically observe and simultaneously quantify surface charge which is not possible using conventional methods. This allows the surface charge distribution under the influence of a time varying electric field to be studied. The system's accuracy and sensitivity have been improved through the use of an Optical Phase Modulator. The system uses a high speed CCD camera with a maximum frame rate of 1000 frames per second and Synchronisation Control Circuit to obtain a high temporal resolution. This has allowed the study of charge behaviour at mains power frequencies.
Surface charge distributions have been observed by applying both impulse and AC voltages to a needle electrode in direct contact with the BSO. AC surface discharge behaviour of polymeric materials bonded to the BSO has also been investigated. The effect of the surrounding environment has been experimentally examined by placing the cell inside a vacuum chamber. Surface charge measurements have been made at various atmospheric pressures. The effect of an electro-negative gas (Sulphur Hexafluoride) on the surface charge distribution has also been investigated.
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Published date: 2001
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Local EPrints ID: 464551
URI: http://eprints.soton.ac.uk/id/eprint/464551
PURE UUID: e71987df-f345-4e84-a8a4-289757d7bfde
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Date deposited: 04 Jul 2022 23:46
Last modified: 16 Mar 2024 19:36
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Author:
Yao Long Sam
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