sekundääriemissiosuhteeseen

Sekundääriemissiosuhde, often abbreviated as S.E.R., is a key parameter in the operation of vacuum tubes and other electron devices. It quantifies the efficiency with which a surface emits secondary electrons when bombarded by primary electrons. When a primary electron strikes a surface, it can transfer enough energy to knock out one or more electrons from the material's atomic structure. These ejected electrons are called secondary electrons.

The secondary emission ratio is defined as the ratio of the number of secondary electrons emitted to the number of primary electrons incident on the surface. A secondary emission ratio greater than one means that more electrons leave the surface than arrive, which is a crucial phenomenon for devices like photomultiplier tubes, where it amplifies the initial signal. Conversely, a ratio less than one indicates that fewer secondary electrons are emitted than primary electrons strike.

Factors influencing the sekundääriemissiosuhde include the material of the emitting surface, the energy of the incident primary electrons, the angle of incidence, and the surface condition. Different materials have varying work functions and electron densities, which affect their propensity for secondary electron emission. Optimizing materials and operating conditions is essential for achieving desired performance in electron-emitting devices. This concept is fundamental to understanding electron amplification and signal processing in vacuum electronics.