Untitled

Abstract

A visualization and a quantification technique for a latent electric charge image on a dielectric material has been developed by using the Pockels effect and a computer imaging technique. An optical phase modulation technique and a computer image lock-in amplifier technique were used to improve the signal-to-noise ratio. The measurement system has several improved performances; sensitivity of surface change of 1 nC cm-2, spatial resolution of 200 mu m and discrimination of charge polarity. The basic principle of advanced electro-optic surface charge measurement is described and the typical surface charge distribution of positive discharge streamer produced by a high impulse voltage (5 kVpeak) is demonstrated. Also, comparison is made between the modulation method and the non-modulation method.

Symmetries of generating functionals of Langevin processes with colored multiplicative noise

“…In magnetism, the motion of the classical magnetic moments of small particles is phenomenologically described by the Landau-Lifshitz-Gilbert equation in which the fluctuations of the magnetic field are coupled multiplicatively to the magnetic moment [7]. Many other examples pertain to soft condensed matter; two of these are confined diffusion, in which the diffusion coefficient of the particle depends on the position via hydrodynamic interactions [8], and the stochastic partial differential equation that rules the time-evolution of the density of an ensemble of N Brownian particles [9]. In a cosmological framework, these equations arise as effective equations of motion for the out of (although close to) equilibrium evolution of self-interacting quantum fields in which the short-wave length modes serve as thermal baths for longer wave-length modes with slower dynamics [10].…”

Charge transfer to a dielectric target by guided ionization waves using electric field measurements

“…Figure17. The maximum electric field values (kV cm −1 ) as a function of discharge length for varying flow.…”

Space Charge Measurement Technologies and Their Potential Applications

“…The pressure pulse techniques have also been used for the measurement of space charge in composite oil/cellulose insulating systems. (21)(22)(23)(24)(25) For the measurement of electric fields and space charge in liquid dielectrics and surface charge on solids in air, the electrooptic Kerr effect technique (26)(27)(28)(29)(30) and Pockels effect technique (31)(32)(33) have been developed. In comparison with the earliest slice method, (34) these latest techniques can be used to measure quantitatively the distribution of space charge in an insulating material nondestructively, and thus are valuable tools in helping to understand the electrical behaviors of an insulation system in the development of power equipment, such as high-voltage direct-current (HVDC) cables ( Fig.…”