Liquid dielectric

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

Liquid deformable mirror for high-order wavefront correction.

Abstract: We propose and demonstrate a novel liquid deformable mirror, based on electrocapillary actuation, for high-order wavefront correction. The device consists of a two-dimensional array of vertically oriented microchannels filled with two immiscible liquids, an aqueous electrolyte, and a viscous dielectric liquid, where the dielectric liquid overfills the top end of the channel and forms a thin layer on top. To remedy the poor reflectivity of pure liquids, a free-floating reflective membrane or a dye-coated liquid can be used. The proposed device offers several advantages for adaptive optics applications. These advantages include a high number of actuators, high stroke dynamic range, low power dissipation, fast response time, an initially flat surface, and low cost. However, the device is mainly suitable for dynamic wavefront correction and is limited by its orientation.

Comparison Between the DC and AC Breakdown Characteristics of Dielectric Sheets in Liquid Nitrogen

Abstract: With the emergence of superconductor technology, high-temperature superconducting (HTS) power devices are quickly being developed. HTS power devices are receiving considerable attention due to their high capacity and low loss. Compared with ac HTS power devices, dc superconducting power devices have the advantage of zero resistance. To aid in the development of superconducting power devices, the ac and dc dielectric breakdown characteristics of dielectric sheets in liquid nitrogen ( LN2) should be better understood. In this paper, results are reported for ac and dc breakdown tests conducted in air (room temperature) on six types of sheets, including polypropylene laminated paper (PPLP), Nomex (polyamide) T410 fiber paper, Kapton (polyimide) 100HN, Kapton 100CR, Kapton 150FN019, and Kapton 150FCR019, and in LN2 on seven types of sheets, including PPLP, Kapton 100HN, Kapton 100CR, Kapton 150FN019, Kapton 150FCR019, Nomex T410, and Nomex T418 fiber paper. The insulation dielectric properties in air (room temperature) were compared with the insulation dielectric properties at a low temperature. At room temperature, the dc breakdown strength at 63.2% probability is 1.12-1.72 times the ac breakdown strength at 63.2% probability, and at a low temperature, the 63.2% probability of the dc breakdown strength is 1.52-2.14 times the 63.2% probability of the ac breakdown strength. Compared with the dielectric sheets of Kapton 150FCR019, Kapton 100CR, Kapton 150FN019, Kapton 100HN, and PPLP, Nomex T410 sheets have shown a remarkable increase in their dielectric strength in liquid nitrogen compared with air.

Study on the Dielectric Characteristics of Gaseous, Liquid, and Solid Insulation Materials for a High Voltage Superconducting Apparatus

Abstract: A study on the dielectric characteristics of various cryogenic materials should be conducted to design an electrically reliable high-voltage superconducting apparatus. Especially, the dielectric characteristics of gaseous and solid insulation materials are important for designing current lead parts, and those of gaseous and solid insulation materials are indispensable for designing superconducting coil parts. A subcooled liquid nitrogen (LN2) cooling system is the most promising, with respect to insulation, thermal stability, and current capacity, in the development of a high-voltage superconducting apparatus. In this paper, dielectric experiments on gaseous nitrogen ( GN2), LN2, and glass fiber reinforced plastic are conducted under ac and lightning impulse voltage for various pressures. Sphere-to-plane electrode systems are used to examine the dielectric characteristics of insulation materials according to field utilization factor (ξ). The experimental results are analyzed by a finite element method. The empirical formulae for calculating the electrical breakdown voltages of various cryogenic insulation materials at sparkover are presented.

Non-thermal plasma ethanol reforming in bubbles immersed in liquids

Abstract: Ethanol reforming in non-thermal plasma generated in atmospheric-pressure argon bubbles immersed in liquid ethanol/water solution is studied using a self-consistent multi-species fluid model. The influence of the dielectric constant of the liquid on the plasma dynamics and its effect on the generation of active species is analyzed. Several modes of discharge are obtained for large liquid dielectric constant. In these modes, we obtain either an axial streamer or a combination of two simultaneous streamers propagating along the bubble axis and near the liquid wall. The influence of these modes on the production of active species is also studied. The main reactions responsible for the generation of molecular hydrogen and light hydrocarbon species are analyzed. A possible mechanism of hydrogen generation in liquid phase is discussed.

Formation of Regions with High Energy and Pressure Gradients at the Free Surface of Liquid Dielectric in a Tangential Electric Field

Abstract: The nonlinear dynamics of the free surface of an ideal incompressible non-conducting fluid with a high dielectric constant subjected to a strong horizontal electric field is simulated using the method of conformal transformations. It is shown that in the initial stage of interaction of counter-propagating periodic waves of significant amplitude, there is a direct energy cascade leading to energy transfer to small scales. This results in the formation of regions with a steep wave front at the fluid surface, in which the dynamic pressure and the pressure exerted by the electric field undergo a discontinuity. It has been demonstrated that the formation of regions with high gradients of the electric field and fluid velocity is accompanied by breaking of surface waves; the boundary inclination angle tends to 90◦, and the surface curvature increases without bound.