Corona Discharge Technology in US Ozone Generators

Corona discharge technology - Corona discharge remains the dominant method for onsite ozone generation.

Corona discharge is an electrical phenomenon that occurs when a current flows from an electrode with a high potential into a neutral fluid, typically air. It happens when the electric field surrounding the conductor becomes so strong that it ionizes the fluid, creating a region of plasma around the electrode. This process is a partial electrical breakdown, meaning it occurs without a full electrical arc, and it is often visible as a bluish glow accompanied by a hissing or crackling sound.

How it Works
The process is a chain reaction known as an "electron avalanche." When a high voltage is applied to an electrode, especially one with a sharp point or curved edge, the electric field strength is concentrated at that location. This strong field is enough to accelerate any free electrons in the air to a high velocity. These energized electrons then collide with neutral gas molecules, such as oxygen and nitrogen, with enough force to knock out other electrons. This creates a chain reaction, as these new free electrons are also accelerated by the electric field and go on to ionize more molecules, creating more electron-ion pairs.

The resulting stream of charged particles (electrons and ions) forms a conductive path, allowing a continuous, albeit low-power, current to "leak" from the electrode into the surrounding air. The bluish glow is the light emitted as electrons and ions recombine.

Applications
While a natural occurrence in high-voltage power lines that is often seen as a problem to be mitigated, controlled corona discharge has numerous useful applications in various industries:

Ozone Generation: Ozone (O 
3
​
 ) is a powerful oxidizing agent used for disinfection and purification. Corona discharge generators are a common way to produce ozone by passing air or pure oxygen through a high-voltage electrical field, where the discharge splits O 
2
​
  molecules, and the resulting single oxygen atoms combine with other O 
2
​
  molecules to form O 
3
​
 . This technology is widely used in water treatment, air purification systems, and for sanitizing swimming pools.

Surface Treatment: In the manufacturing industry, corona discharge is used to modify the surface of materials, especially plastics and films. By exposing a material's surface to a corona, its surface energy is increased, making it more receptive to inks, adhesives, and coatings. This is crucial for applications like printing on plastic packaging or ensuring a strong bond between different layers of a product.

Air Ionization and Filtration: Corona discharge is a key component in electrostatic precipitators, which are used to remove particulate matter from gas streams. The corona charges airborne particles, which are then attracted to and collected on plates with an opposite charge, effectively cleaning the air.

Static Control: Corona discharge can be used to neutralize static electricity on surfaces in manufacturing or printing processes, preventing problems like dust accumulation and material jamming.

Undesirable Effects
In high-voltage electrical power transmission, corona discharge is an unwanted side effect that causes:

Energy Loss: The discharge dissipates power, leading to reduced efficiency in the transmission system.

Audible Noise and Radio Interference: The crackling sound and electromagnetic interference can be disruptive.

Material Degradation: The ozone and other corrosive byproducts generated by the discharge can degrade the insulation and conductors over time.