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Contrasting differences between discrete and continuous electron multipliers. An electron multiplier is a vacuum-tube structure that multiplies incident charges. [1] In a process called secondary emission, a single electron can, when bombarded on secondary-emissive material, induce emission of roughly 1 to 3 electrons.
By applying a strong electric field across the MCP, each individual microchannel becomes a continuous-dynode electron multiplier. A particle or photon that enters one of the channels through a small orifice is guaranteed to hit the wall of the channel, due to the channel being at an angle to the plate.
Each electron that strikes the surface of the second dynode produces several more electrons, which are then accelerated toward the third dynode, and so on. By the time this process has been repeated at each of the dynodes, 10 5 to 10 7 electrons have been produced for each incident photon, dependent on the number of dynodes.
The electron multiplier consists of a number of electrodes called dynodes. Each dynode is held at a more positive potential, by ≈100 Volts, than the preceding one. A primary electron leaves the photocathode with the energy of the incoming photon, or about 3 eV for "blue" photons, minus the work function of the photocathode. A small group of ...
With an electron multiplier an impact of a single ion starts off an electron cascade, resulting in a pulse of 10 8 electrons which is recorded directly. A microchannel plate detector is similar to an electron multiplier, with lower amplification factor but with the advantage of laterally-resolved detection.
Each incident electron produces multiple secondary electrons, so the cascaded dynode chain amplifies the initial electrons. In particle physics , secondary emission is a phenomenon where primary incident particles of sufficient energy , when hitting a surface or passing through some material, induce the emission of secondary particles.
The electron cloud moves between the inner and outer conductor in resonance, causing an electron avalanche: in 5 nanoseconds, the number of electrons increases 150×. [ 1 ] The multipactor effect occurs when electrons accelerated by radio-frequency (RF) fields are self-sustained in a vacuum (or near vacuum) via an electron avalanche caused by ...
The most commonly used detector setup is an electron bombardment ion source followed by a mass filter and an electron multiplier. The beam is directed through a series of differential pumping stages that reduce the noise-to-signal ratio before hitting the detector. A time-of-flight analyzer can follow the detector to take energy loss measurements.