breakdown potential

Breakdown potential

The potential difference at which an electrically stressed gas is transformed from an insulator to a conductor. In an electrically stressed gas, as the voltage is increased, the free electrons present in the gas gain energy from the electric field. When the applied voltage is increased to such a level that an appreciable number of these electrons are energetically capable of ionizing the gas, the gas makes the transition from an insulator to a conductor; that is, it breaks down. The potential difference at which this transition occurs is known as the breakdown potential for the particular gaseous medium.

The breakdown potential depends on the nature, number density, and temperature of the gas; on the material, state, and geometry of the electrodes; on the type of voltage applied (steady, alternating, impulsive); and on the degree of preexisting ionization. Areas of surface roughness at the electrodes (especially the cathode) or the presence of conducting particles in the gas greatly reduces the breakdown potential because at such points the electric field is significantly enhanced, increasing the electron energies and thus gas ionization. The breakdown voltage varies considerably from one gaseous medium to another; it is very low for the rare gases, and very high for polyatomic, especially electronegative, gases such as sulfur hexafluoride (SF6).

The transition of a gas from an insulator to a conductor under an imposed electrical potential occurs in times ranging from milliseconds to nanoseconds, depending on the form of the applied field and the gas density. This transition depends on the behavior of electrons, ions, and photons in the gas, especially the processes which produce or deplete free electrons. Knowledge of these processes often allows prediction of the breakdown voltage of gases and the tailoring of gas mixtures which can withstand high electrical potentials for practical uses. See Electrical breakdown, Electrical conduction in gases

The systematic development of gaseous dielectrics with high dielectric strength (that is, high breakdown potential) is most significant for high-voltage technology, which has a multiplicity of gas insulation needs. Dielectric gases are widely used as insulating media in high-voltage transmission lines, circuit breakers, transformers, substations, high- voltage research apparatus, and other electrical equipment. See Dielectric materials

breakdown potential

[′brāk‚dau̇n pə′ten·shəl]
References in periodicals archive ?
The minimum cathode capacitance required to keep its voltage below the breakdown potential of the electrolyte is thus Cc = CaVa/Vc where Vc is set to 0.
British Pound: UK Data, BOE Decision Present Breakdown Potential Fundamental Forecast for British Pound: Bearish - UK GDP was revised to -0.
The process temperature is positively related to cell reductions due to a decreasing elastic modulus and critical breakdown potential in the cell membrane.
Investigation of 316L stainless steel and Ti-6Al-4V in deaerated simulated body fluid Hank's solution at 37[degrees]C have revealed a high breakdown potential for Ti-6Al-4V (1900 mV vs.
The passivation parameters like breakdown potential ([E.
The breakdown potential (Eb) of the Ti alloys, excepting Ti-15Al, were comparable (Table 1).
The Ti-15Al alloy exhibited a lower breakdown potential as compared to other Ti alloys.
Japanese Yen to Follow Risk Trends as Prices Test Key Resistance British Pound: UK Data, BOE Decision Present Breakdown Potential Swiss Franc Support Looks To Continue Despite SNB Threat Canadian Dollar Confronts its Own Employment Change Data Australian Dollar Rally May Finally Be Losing Steam New Zealand Dollar At Risk of Turn Lower on Extreme Sentiment
2 V), where breakdown potentials are shifted towards more positive values, almost in the transpassive region.
3] ALD coatings strongly improve the corrosion resistance of stainless steels in chloride-containing media decreasing by at least two orders of magnitude the passive current density and shifting breakdown potentials towards more positive values.
But poor vacuums are the antithesis of high breakdown potentials.