Hollow cathode effect explained

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.

Notes and References

1. Eichhorn. H.. Schoenbach. K. H.. Tessnow. T.. Paschen's law for a hollow cathode discharge. Applied Physics Letters. 63. 18. 1993. 2481–2483. 0003-6951. 10.1063/1.110455. June 5, 2017. 1993ApPhL..63.2481E. August 8, 2017. https://web.archive.org/web/20170808052224/https://www3.nd.edu/~sst/teaching/AME60637/reading/1993_APL_Schoenbach_et_al_hollow_cathode.pdf. dead.
2. Paschen. F.. Bohrs Heliumlinien. Annalen der Physik. 355. 16. 1916. 901–940. 0003-3804. 10.1002/andp.19163551603. 1916AnP...355..901P.
3. Bartlow. Robert B.. Griffin. Steven T.. Williams. J. C.. Axial evolution of the negative glow in a hollow cathode discharge. Analytical Chemistry. 64. 22. 2002. 2751–2757. 0003-2700. 10.1021/ac00046a017. 1294005 .
4. Mavrodineanu. R.. Hollow Cathode Discharges - Analytical Applications. Journal of Research of the National Bureau of Standards. 89. 2. 1984. 143–185. 0160-1741. 34566122. 10.6028/jres.089.009 . 6768240 . free.