Corona discharge

Corona discharge 1

Коронный разряд

Nje shkarkese korone ne nje luge

National Bureau of Standards high voltage laboratory

Corona Discharge Collage

Corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor that is electrically charged. This phenomenon occurs in high voltage systems, including overhead electrical power lines, and around sharp objects when the electric field strength exceeds a critical value. This critical value causes the air, or another fluid, to become conductive, leading to ionization and the emission of light and noise. Corona discharge plays a significant role in various scientific and industrial applications, but it can also lead to power loss in electrical systems and is a source of electromagnetic interference.

Mechanism

The mechanism of corona discharge begins when the electric field strength around a conductor is strong enough to form a conductive region, but not strong enough to cause electrical breakdown or arc discharge. In this state, the air or other fluid around the conductor becomes ionized, creating a plasma sheath around the conductor. This ionization process is self-sustaining at high electric field strengths, leading to a continuous discharge as long as the conditions are met.

Types

There are two main types of corona discharge: positive and negative. Positive corona discharge occurs when the conductor has a positive charge, and it tends to form smoother, more diffuse glow around the conductor. Negative corona discharge, on the other hand, occurs with negatively charged conductors and tends to be more focused and intense. The type of corona discharge can affect its properties, including the color of the emitted light and the efficiency of ion production.

Applications

Corona discharge has both beneficial and detrimental applications. In industrial processes, it is used for surface treatment, ozone generation, and in electrostatic precipitators for air purification. The corona effect is also utilized in photocopiers and laser printers for depositing toner on paper. However, in electrical power transmission, corona discharge represents a significant challenge as it leads to power loss, noise, and electromagnetic interference. Efforts to minimize corona effects in power systems include designing conductors with larger diameters and smoother surfaces.

Detection and Measurement

Detecting and measuring corona discharge is crucial for maintaining electrical systems and for research purposes. Techniques include using ultraviolet and infrared cameras, which can detect the light emitted by corona discharges that is not visible to the human eye, and specialized sensors that can detect the electromagnetic emissions from corona discharges.

Environmental Impact

Corona discharge can have environmental impacts, including the production of ozone and nitrogen oxides, which are harmful pollutants. The ozone generated by corona discharge can contribute to the degradation of materials and is a health hazard at ground level.

See Also

• Electric field
• Plasma (physics)
• Electrical breakdown
• Ozone
• Electrostatic precipitator