Aston Dark Space

The Aston Dark Space is a region in the demonstration apparatus consisting of a nearly evacuated tube with electrodes at each end.

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When a cathode is bombarded by positive ions coming mainly from the negative glow region, where they are created by collisions with fast electrons. These ions recombine at the cathode, then fall to the ground state with the emission of light. This light constitutes the cathode glow, which is separated from the cathode by a very narrow dark interval, the Aston dark space. The "dark" regions are not really dark, just less luminous than the bright regions.

Related Topics:
Cathode - Ion

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