Kylmäkatodipurskaus

Kylmäkatodipurskaus refers to a type of electrical discharge that occurs in a gas at relatively low pressure. Unlike a hot cathode discharge, where a filament is heated to emit electrons, a cold cathode discharge relies on field emission or secondary electron emission from the cathode surface to initiate and sustain the plasma. This means the cathode does not need to be heated to a high temperature for the discharge to occur.

The process typically starts with a small number of free electrons in the gas. When a sufficiently high voltage is applied between the cathode and anode, these electrons are accelerated. As they collide with gas atoms, they can ionize them, creating more electrons and positive ions. This cascade effect leads to the formation of a plasma. Positive ions are accelerated towards the cathode, and their impact can cause secondary electron emission, further sustaining the discharge.

Kylmäkatodipurskaus is characterized by a lower operating temperature compared to hot cathode discharges, which can be advantageous in certain applications where heat generation needs to be minimized or where the cathode material is sensitive to high temperatures. Common examples include neon signs, some types of fluorescent lamps, and early forms of vacuum tubes. The breakdown voltage and current density depend on the gas type, pressure, and electrode geometry.