Sekundääriemis

Sekundääriemis is a term used in Finnish to describe a secondary emission. Secondary emission occurs when a material is bombarded by primary particles, such as electrons, ions, or photons, and in response, emits other particles. These emitted particles are called secondary particles. The type of secondary particles emitted depends on the primary particles and the target material. For example, electron bombardment of a solid surface can result in the emission of secondary electrons, as well as reflected primary electrons and sometimes even Auger electrons.

The phenomenon of secondary emission is important in various fields. In vacuum tube technology, it can lead to unwanted effects like secondary emission noise. However, it is also exploited in devices like photomultiplier tubes, where a small number of initial photons can trigger a cascade of secondary electrons, amplifying the signal. Secondary emission also plays a role in the operation of cathode ray tubes and in plasma physics. The yield of secondary emission, often denoted by the symbol delta (δ), is defined as the ratio of the number of secondary particles emitted to the number of primary particles incident on the surface. This yield is highly dependent on the energy of the incident particles and the properties of the target material.