Kerr effect in gas and its application to noncontact measurement of electric field

Abstract

A noncontact measurement of electric field is proposed based on the Kerr effect in gases. With the Kerr sensing technique, the electric field can be measured without causing any field disturbance. Kerr constants of gases are, however, very small compared with those of liquids, and this ideal technique has not been applied to electric field measurement in gas. In this study, a system is developed for a highly sensitive measurement of the small phase retardation caused by the Kerr electro-optic effect in gases. An optical phase modulation technique is effectively adopted to improve the sensitivity of the system. With this optical system, (i) dc stressed uniform electric fields in sulfur hexafluoride, nitrogen, and carbon dioxide gases at the pressure of 0.2–0.5 MPa and (ii) ac stressed uniform electric fields in atmospheric air are measured.

Applicability of the Kerr effect in remote sensing of thunderstorm electric fields

“…The phase shift (rad) for light with the wavelength λ 0 = 500 nm, where n and n 0 are the indices of refraction of air in the region sensed and at sea level, respectively [3]. The strength of typi cal thunderstorm electric fields E = 100 kV/m.…”

High voltage measuring apparatus based on kerr effect in gas

“…To realize the improvement of sensitivity and the perfectly non-contact field measurement, an optical phase modulation technique [11,13] is used. The light beam emitting from a stabilized He-Ne laser of 3 mW passes through a photoelasticmodulator (PEM) and is put into the White cell.…”

“…The Kerr constants of gases are smaller than those of liquid by more than an order of four. By utilizing optical phase modulation technique to improve the sensitivity of the measuring system, the perfectly non-contact field measurement has been realized based on Kerr effect in atmospheric air, and in 0.2 to 0.5 MPa SF 6 , N 2 , and CO 2 gases, and succeeded in measuring 50 Hz ac and dc field [11].…”

A novel technique for remote sensing of thunderstorm electric fields via the Kerr effect and sky polarization

“…This difference results in a phase shift where l is the path length and λ 0 is the vacuum wavelength. The effect is small in air and is directly proportional to the density, with K ≃ 2.3 × 10 −25 m 2 V −2 at sea level [ Weinheimer , 1985; Kumada et al , 2002].…”