Secondary Electron Emission Phenomena in Vacuum Systems

In vacuum environments such as particle accelerators, space propulsion systems and high-power radio-frequency devices, secondary electron emission occurs when primary electrons impinge on a surface and liberate additional electrons. This phenomenon is governed by material properties, surface chemistry and morphology. When secondary electron yield exceeds unity, avalanches of electrons may form, leading to electron clouds and multipactor discharges that degrade device performance, induce vacuum pressure rises and generate electromagnetic instabilities. Contemporary research has focused on tailoring surface composition and topography to suppress unwanted emission, employing coatings, engineered nanostructures and in situ conditioning to achieve stable secondary electron yield below unity. Such advances are critical for the reliable operation of next-generation accelerators, satellite electronics and compact vacuum sensors, where control of electron-induced effects underpins both efficiency and longevity.

Research from Nature Portfolio

Recent studies have elucidated how carbon-based adsorbates interact with copper substrates to modulate secondary emission. Simulations combining first-principles calculations, molecular dynamics and Monte Carlo methods reveal that carbon pairs and graphitic-like layers can either enhance or suppress emission depending on coverage. Experiments confirm that exposure to electron irradiation induces bond reorganisation from atomic carbon to graphitic films, with the latter exerting the strongest damping effect on secondary electrons. Charge density analyses demonstrate that surface morphology and electronic structure variations at the copper–carbon interface are key determinants of secondary electron yield.

Secondary Electron Emission Phenomena in Vacuum Systems publication trend

The graph below shows the total number of articles in secondary electron emission phenomena in vacuum systems across all publications each year (not limited to Nature Index journals).

Technical terms

Secondary electron yield (SEY): the ratio of emitted secondary electrons to incident primary electrons upon surface impact.

Electron cloud: a collective of accumulated secondary electrons in a vacuum enclosure, often leading to beam instabilities and pressure rises.

Multipactor effect: a resonant secondary emission discharge in radio-frequency systems triggered by repeated electron impact and acceleration.

Work function: the minimum energy required to remove an electron from a solid surface to the vacuum level.

Surface morphology: the micro- and nanoscale topographical features of a material that influence electron emission characteristics.

References

1. The Role of Hydrogen Incorporation into Amorphous Carbon Films in the Change of the Secondary Electron Yield. International Journal of Molecular Sciences (2023).
2. Suppression of Secondary Electron Emission from Nickel Surface by Graphene Composites Based on First-Principles Method. Nanomaterials (2023).
3. Importance of surface morphology on secondary electron emission: a case study of Cu covered with carbon, carbon pairs, or graphitic-like layers. Scientific Reports (2023).