Liquid dielectric

About: Liquid dielectric is a research topic. Over the lifetime, 3702 publications have been published within this topic receiving 45150 citations.

A liquid ionization chamber with high spatial resolution

Abstract: An ionization chamber is described having a sensitive volume of 2 mm3 and employing a dielectric liquid as the ionization medium. The fundamental properties of general saturation, temperature dependence and radiation quality dependence for electron radiation are given. The usefulness of the chamber is illustrated by measurements of absorbed dose build-up at the surface of, and the absorbed dose distribution behind, a conventional ionization chamber in a polystyrene phantom irradiated with high energy electrons.

Electrohydrodynamic instability of a rotating layer of a viscoelastic fluid heated from below

Abstract: The stability of a rotating layer of viscoelastic dielectric liquid (Walters’ liquid B’) heated from below is considered. Linear stability theory is used to derive an eigenvalue system of ten orders and exact eigenvalue equation for a neutral instability is obtained. Under somewhat artificial boundary conditions, this equation can be solved exactly to yield the required eigenvalue relationship from which various critical values are determined in detail. Critical Rayleigh heat numbers and wavenumber for the onset of instability are presented graphically as function of the Taylor number for various values of electric Rayleigh number and the elastic parameters.

Conductivity relaxation in positive dielectric liquid crystals

Abstract: Measurements are reported of the frequency dependence of the conductivities σ⊥ and σ∥ in some nematic liquid crystals with strong positive dielectric anisotropy which are nematic at room temperature. The conductivity relaxation which causes σ∥ to increase already at frequencies <100 Hz in highly deionized liquid crystals are shown to be quantitatively in agreement with the dispersion of the orientation polarization of the molecules. The magnitude and sign of the conduction anisotropy σ∥−σ⊥ is shown to be strongly frequency dependent. The relaxation times τ⊥ and τ∥ due to the respective rotation of the molecules in a plane perpendicular and parallel to their long axes were determined.

Kerr electro-optic field measurement and charge dynamics in transformer-oil/solid composite insulation systems

Abstract: We measured the electric field in transformer oil/solid composite insulation system under dc voltage application using a Kerr electro-optic measurement system. When a pressboard was inserted at the center between two parallel-plane electrodes, the electric field at the mid-point between the pressboard and the cathode decreased with time. On the other hand, the electric field at the mid-point between the pressboard and the anode increased initially with time, reached a maximum value and then fell down. We measured also the electric field before and after polarity reversal of the dc voltage. The results revealed that the electric field after polarity reversal reached a magnitude 2.7/spl times/ as much as the average dc applied field. We interpreted the above results on the time transition of the electric field in terms of a charge dynamic model, considering the difference in charge accumulation speed on the pressboard between positive and negative charges. This model was verified to be applicable to the time transition of the electric field in oil/solid composite system and BTA added oil/solid composite system as well.