Ionization in the circuit breaker is facilitated by

Ionization in the circuit breaker is facilitated by

Right Answer is:

All of the above

SOLUTION

Ionization of gas in  circuit breaker depends upon

  1. Temperature
  2. Mean free path
  3. Electric field strength

Temperature: At high temperatures, the kinetic energy of gaseous particles increases, and energy transfer through collisions causes thermal dissociation and/or thermal ionization. The rate of thermal dissociation or ionization of a particle (molecule or atom) into several particles (atoms, ions, or electrons) is theoretically given as a function of temperature; that is, the thermal dissociation or ionization equilibrium is determined by an equilibrium coefficient that increases considerably with temperature.

Electric Field Strength:- The basic phenomenon of ally discharge. including a spark. is tl~e ionization of gas atoms and molecules by electron impact. The ionization rate depends dramatically on the electric field strength, so it is only in sufficiently strong fields that the rate may become high enough to produce a plasma. The quantitative criterion for sufficiently strong fields’ varies with the gas am other conditions.

Mean Free Path:- In physics, the mean free path is the average distance traveled by a moving particle (such as an atom, a molecule, a photon) between successive impacts (collisions). As the pressure is reduced, and the mean free path increases, the energy gained by an electron from the applied field increases, and the effective electron temperature rises.

The energy gained is proportional to the product of the mean free path and the applied field strength E, and since the mean free path is inversely proportional to the pressure p it follows that the conditions are a function of E/p. At low values of E/p, the energy gained by an electron between collisions is small, and it makes only elastic collisions with the gas molecules, but at high values of E/p the mean electron temperature rises and the number of electrons in the high energy tail of the energy distribution increases rapidly. 

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