veldemissiebron

Vel-demissiebron is a term used in some Dutch-language technical texts to denote a field emission source, a device that emits electrons from a solid surface under the influence of a strong electric field. The word combines veld (field), emissie (emission), and bron (source); in English-language literature the concept is usually called a field emission source or cold cathode emitter. The term is more common in certain engineering contexts and is not universally used in English across disciplines.

Principle and operation: Field emission occurs when the electric field at a surface is intense enough to lower the potential barrier for electrons, allowing them to tunnel through the barrier rather than relying on thermal energy. Emission is typically described as a cold process, in contrast to thermionic emission. The current–voltage relationship is analyzed using Fowler–Nordheim theory, and practical devices rely on nanoscale sharp geometries to concentrate the local electric field and boost emission.

Variants and applications: Common implementations include arrays of sharp metal tips (such as Spindt-type emitters), vertically aligned carbon nanotube emitters, and graphene-based emitters. Vel-demissiebrons are used as electron sources in applications such as electron microscopes, vacuum microelectronic devices, certain X-ray sources, and electron guns for accelerators. Design considerations cover tip geometry, material work function, vacuum quality, gating, emission uniformity, and long-term stability.

History and context: Field emission as a general concept emerged in early 20th-century physics, with practical cold-cathode devices developed in the mid-20th century. Vel-demissiebron remains a term tied to Dutch-language discussions of these technologies in engineering and applied physics.