electron multiplier

electronics

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mass spectrometry

  • Figure 1: An electron bombardment ion source in cross section. An electron beam is drawn from the filament and accelerated across the region in which the ions are formed and toward the electron trap. An electric field produced by the repeller forces the ion beam from the source through the exit slit.
    In mass spectrometry: Electron multipliers

    The development of electronic techniques for television during the 1930s yielded a device of extraordinary sensitivity for measuring small electron beams—namely, the secondary electron multiplier. Although originally invented for the amplification of the tiny currents from a photocathode, it soon proved to be…

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photocathodes

  • detector output connected to a measuring circuit
    In radiation measurement: Conversion of light to charge

    …that multiplies the number of electrons by a factor of typically 105 or 106. The electron multiplication takes place along a series of electrodes called dynodes that have the property of emitting more than one electron when struck by a single electron that has been accelerated from a previous dynode.…

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grid, in an electron tube, an electrode that has openings for controlling the flow of electrons or ions through it. Unmodified, the term applies to a control grid that is ordinarily placed between the cathode and the anode (or plate) of an electron tube to vary the flow of current. A screen grid—usually maintained at a fixed potential—is placed between a control grid and an anode to reduce the electrostatic influence of the anode on the control grid. A suppressor grid is interposed between two positive electrodes—usually the screen grid and the anode—to reduce the flow of secondary electrons from one to the other.

This article was most recently revised and updated by William L. Hosch.