Potential distribution measurement of surface discharge by Pockels sensing technique

Abstract

A new technique for measuring the transient potential distribution of electrical discharge is proposed. The measuring system consists of a Bi4Ge3O12 Pockels crystal, an Ar ion laser, a beam expander, a streak camera and a charge-coupled device camera. The potential profile of the discharge along a linear path of 50 mm in length is measured in the range of 0∼±36 kV. The temporal and spatial resolutions of this system are estimated to reach 2 ns and 0.1 mm, respectively. The potential distribution of a surface discharge creeping on a dielectric material is measured to clarify its developing mechanism. The tip of the propagating surface discharge has a high potential close to an applied potential. The maximum value of electric fields of a negative surface streamer exceeds 16 kV/cm in the direction of the streamer propagation.

Nanosecond surface discharge and charge density evaluation Part I: review and experiments

“…Recently, one of authors, T. Takada [23], [24], devised a new technique using a Pockels effect with which the discharge pattern and the charge density distributions produced due to the surface discharge development can be measured two-dimensionally and dynamically, and succeeded in simultaneously and separately recording the positive and negative charge distributions using a computer graphic technique. Another of the authors, K. Hidaka [25], [26], applied this technique to study the nanosecond surface discharge phenomena with a potential probe and a ultra-high-speed camera techniques. The present paper describes not only the developing velocity of corona streamers measured optically using the dust figure method, but also the mechanism of nanosecond surface discharge development, based on the mobility of positive and negative charge particles and the charge accumulation effect.…”

Development of an electric field sensor based on second harmonic generation with electro-optic materials

“…1. Here a laser with a frequency ω is incident upon a crystal for which the second-order susceptibility χ (2) is nonzero. The second-order polarization created in such a crystal consists of a contribution at frequency 2ω and this contribution leads to the generation of electromagnetic radiation at the second-harmonic frequency 2ω.…”

“…The proposed technique possesses following characteristics, which can be advantageously utilized for electric field sensing. (1) It incorporates direct measurement of the SHG output intensity and not the phase change of the transmitting light beam as in the case of Pockels method, therefore higher signal to noise ratio can be expected; (2) Different types of nonlinear, electro-optic crystals can be considered for such application. In recent years, lithium niobate (LiNbO 3 , LN) is being widely used in electro-optic devices [11].…”

“…Optical sensors are also useful in the measurement of impulse electric fields where high electrical noise and interference conditions, such as those produced during lightning strokes, switching surges, and electric-discharge experiments, result in expensive and difficult electrical isolation. Traditionally, these optical sensors utilize electro-optic effect (Pockels effect), and they have been widely used for monitoring voltages and electric fields [2][3][4]. Fiber-optic based electric field sensors have also been reported by different research groups.…”

Intense transient electric field sensor based on the electro-optic effect of LiNbO3

“…6 Therefore, sensors based on the electro-optic effect have been developed by a number of researchers to overcome the above problems. [7][8][9][10][11] Various electric-optic sensors have been developed since the 1970s. Some of the research work has been performed with the aim of measuring high voltages and high electrical fields.…”