Field Electron Emission: How Much Charge Can You Remove From a Sphere?

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SUMMARY

The discussion focuses on the phenomenon of field electron emission from a metal sphere when negative charge is continuously added or removed. It establishes that the discharge of the sphere is primarily influenced by the work function of the material. When negative charge is removed, positive charge accumulates on the sphere's surface, and the discussion explores the threshold at which the metal's skin begins to shed. The balance between ionic (Coulomb) forces and Van der Waals/London forces is critical in determining the stability of the metal lattice under these conditions.

PREREQUISITES
  • Understanding of field electron emission principles
  • Knowledge of work function in materials
  • Familiarity with Coulomb and Van der Waals/London forces
  • Basic concepts of charge accumulation in conductive materials
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  • Research the work function of various metals and its impact on electron emission
  • Explore the principles of Coulomb forces in charged systems
  • Study the Van der Waals/London forces and their role in material stability
  • Investigate experimental methods for measuring field electron emission
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Physicists, materials scientists, and electrical engineers interested in charge dynamics and electron emission phenomena in conductive materials.

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If you have a sphere of metal electrically isolated by a vacuum, and continuously add negative charge to it, the metal will eventually discharge due to field electron emission. This depends primarily on the work function.

Take the same situation as above, but continuously remove negative charge from the sphere. I know that the positive charge will accumulate on the outside of the metal sphere - how much negative charge can you remove before the skin of the sphere starts shedding?
 
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Probably a lot more, the positive charge are the ions of the metal atoms that are being held in the lattice. The electrons are the charges that are mobile and easily stripped off. To expell the ions you would probably have to compare the resulting ionic (Coulomb) forces with the Van der Waals/London forces that hold the metal lattice together.
 

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