Is it possible for electricity to jump a vacuum gap?

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SUMMARY

Electricity can indeed jump a vacuum gap, a phenomenon known as field emission. This occurs under high electric field gradients, allowing electrons to escape from a surface into a vacuum. In vacuum tubes, this process is facilitated by thermionic emission, where electrons flow from heated cathodes to anodes, generating plate current. The voltage required for arcing in a vacuum is significantly higher than in air, estimated at around 30 kV per inch.

PREREQUISITES
  • Understanding of thermionic emission in vacuum tubes
  • Knowledge of field emission principles
  • Familiarity with electrical arcing concepts
  • Basic grasp of electron flow and high voltage applications
NEXT STEPS
  • Research the principles of thermionic emission in vacuum tubes
  • Explore field emission and its applications in modern electronics
  • Study the characteristics of electrical arcing in different mediums
  • Investigate the role of high voltage in electron acceleration and x-ray production
USEFUL FOR

This discussion is beneficial for electrical engineers, physicists, and anyone interested in the principles of vacuum technology and electron behavior in high-voltage environments.

mcjosep
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Is it possible for electricity to jump a vacuum gap? If so, what is it called when that happens?
 
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Yes. Otherwise those old Fleming tubes wouldn't work...
Arching or conduction depending on the amount of current and suddenness of onset.
It takes more voltage to get it going since air and moisture make better conduction paths. I seem to remember 30Kv/inch for an electrical arc in a vacuum, but I could be way off.
 
Before transistors, radio and TV sets used vacuum tubes, which are based on electron flow.
 
mcjosep said:
Is it possible for electricity to jump a vacuum gap? If so, what is it called when that happens?
In vacuum tubes, the electron current is called thermionic emission and plate current. The current is not visible, but the plates sometimes turn red hot.

With very high electric field gradients in very vacuum, field emission of electrons is possible, with lots of x-rays as the accelerated electrons hit the other side.

Bob S
 

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