Difference between Corona Discharge and Dielectric Breakdown?

[jaumzaum]

What's the difference between Corona Discharge and Dielectric Breakdown? For me both stand for the same process, but wikipedia (as many other sites) says they are different. Actually they say corona discharge occurs when the electric gradient is high but not enough to create an electrical breakdown. But I still do not understand the difference about them. Can anyone help me?

 

[Drakkith]

From wiki:

Thermodynamically, a corona is a very nonequilibrium process, creating a non-thermal plasma. The avalanche mechanism does not release enough energy to heat the gas in the corona region generally and ionize it, as occurs in an electric arc or spark. Only a small number of gas molecules take part in the electron avalanches and are ionized, having energies close to the ionization energy of 1 - 3 ev, the rest of the surrounding gas is close to ambient temperature.

I think this is the key. Not only is the plasma different, in a dielectric breakdown you would get a spark or arc from current flowing through the ionized plasma. This doesn't seem to happen in coronal discharge. The field strength isn't high enough to cause such a high amount of breakdown.

 

[lunaloca]

Hi there,

Yes,I agree with Drakkith. Corona discharge is a weakly ionised non-equilibrium plasma based on the avalanche mechanism. If it reaches close distance with a conductive material or you increase the electrical field, it can create longer breakdown streamers and eventually create sparks. Can you please explain what you mean by dielectric breakdown?

 

[voko]

In a dielectric breakdown, two conductors are connected by a well conducting channel made of ionized air. The current in that channel can be very high. In a corona, conductors are not connected by a well conducting channel, the charge is carried by a relatively small number of ions and electrons slowly diffusing through largely neutral gas. The current afforded by that transport is not very high.

 

[sardar]

Corona discharge and dielectric breakdown are both terms used to describe phenomena that occur in the presence of high electric fields. While they may seem similar, there are some important differences between these two processes.

Corona discharge is a type of electrical discharge that occurs when the electric field is high enough to ionize the air surrounding a conductor, but not high enough to cause a complete breakdown of the insulation. This results in a faint glow or corona around the conductor. Corona discharge is often seen in high voltage transmission lines and can cause power loss and interference in electronic equipment.

On the other hand, dielectric breakdown refers to the complete breakdown of the insulating material between two conductors, resulting in a flow of current. This can occur at a lower electric field than corona discharge and can cause damage to the insulation and equipment. Dielectric breakdown is often seen in electrical systems when there is a large surge of voltage, such as during a lightning strike or power surge.

In summary, the main difference between corona discharge and dielectric breakdown is the severity and extent of the electrical discharge. Corona discharge is a mild form of electrical discharge that does not cause complete breakdown, while dielectric breakdown is a more severe and damaging form of electrical discharge.