Hollow cathode effect

The hollow cathode effect allows electrical conduction at a lower voltage or with more current in a cold-cathode gas-discharge lamp when the cathode is a conductive tube open at one end than a similar lamp with a flat cathode.[1] The hollow cathode effect was recognized by Friedrich Paschen in 1916.[2]

In a hollow cathode, the electron emitting surface is in the inside of the tube. Several processes contribute to enhanced performance of a hollow cathode:

  • The pendulum effect, where an electron oscillates back and forth in the tube, creating secondary electrons along the way
  • The photoionization effect, where photons emitted in the tube cause further ionization
  • Stepwise ionization[1]
  • Sputtering[3][4]

The hollow cathode effect is utilized in the electrodes for neon signs, in hollow-cathode lamps, and more.

References
  1. Eichhorn, H.; Schoenbach, K. H.; Tessnow, T. (1993). "Paschen's law for a hollow cathode discharge" (PDF). Applied Physics Letters. 63 (18): 2481–2483. Bibcode:1993ApPhL..63.2481E. doi:10.1063/1.110455. ISSN 0003-6951. Retrieved June 5, 2017.
  2. Paschen, F. (1916). "Bohrs Heliumlinien" (PDF). Annalen der Physik. 355 (16): 901–940. Bibcode:1916AnP...355..901P. doi:10.1002/andp.19163551603. ISSN 0003-3804.
  3. Bartlow, Robert B.; Griffin, Steven T.; Williams, J. C. (2002). "Axial evolution of the negative glow in a hollow cathode discharge". Analytical Chemistry. 64 (22): 2751–2757. doi:10.1021/ac00046a017. ISSN 0003-2700.
  4. Mavrodineanu, R. (1984). "Hollow Cathode Discharges - Analytical Applications". Journal of Research of the National Bureau of Standards. 89 (2): 143. doi:10.6028/jres.089.009. ISSN 0160-1741.
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