# Field Evaporation of Contact Charged Spheres: Exploring Possibilities

• BrandonBerchtold
In summary, if a small ~1 mm diameter sphere is positively charged using a Van de Graaff generator and the charge is high enough to cause field evaporation, the rate of evaporation would increase exponentially as the field strength decreases with the sphere radius. However, the evaporated particles may reduce the positive charge of the sphere enough to prevent further field evaporation. If the sphere is charged to a voltage much higher than the point of significant field evaporation, it may potentially explode. To calculate the field strength at the surface of the sphere, one can use the method of images for a charged sphere above a perfectly conducting electrode, and then compute the force on each element of the sphere using F=dqE.
BrandonBerchtold
If you were to positively contact charge a small ~1 mm diameter sphere using a Van de Graaff generator, and were to charge it sufficiently high enough that field evaporation began to occur, what would happen?

Would the rate of evaporation increase exponentially as the field strength would increase with decreasing sphere radius? Or would the evaporated particles reduce the positive charge of the sphere enough to prevent further field evaporation?

Alternatively, what if you contact charged a small ~1 mm sphere to a voltage much higher than that at which significant field evaporation occurs. Would it explode?

Don't know the answer but here's a suggestion for getting it. A small conducting sphere (particle) coming in contact with a high voltage electrode would be brought to the potential of the electrode. Assume a flat perfectly conducting (PEC) electrode. A charged sphere above a PEC is a canonical problem (method of images if I recall). This calculation would give the field strength at the surface of the particle. Knowing this one may compute the force on each element of the particle as ##F=dq E##.

## 1. What is field evaporation?

Field evaporation is a process in which a solid material is heated in the presence of a strong electric field, causing atoms or molecules to be removed from the surface of the material.

## 2. How does field evaporation of contact charged spheres work?

In field evaporation of contact charged spheres, a strong electric field is applied to a sphere that has been charged through contact with another object. The electric field causes atoms or molecules to be removed from the surface of the sphere, resulting in a change in its shape and size.

## 3. What are the potential applications of field evaporation of contact charged spheres?

Field evaporation of contact charged spheres has potential applications in nanotechnology, materials science, and surface science. It can be used to study the properties of materials at the atomic level and to create new materials with specific properties.

## 4. Are there any challenges or limitations to field evaporation of contact charged spheres?

One challenge of field evaporation of contact charged spheres is the difficulty in controlling the electric field and temperature to achieve a desired shape and size change. Additionally, the process is highly dependent on the properties of the material being studied, making it difficult to generalize results.

## 5. How is field evaporation of contact charged spheres different from other forms of field evaporation?

Field evaporation of contact charged spheres is unique in that it involves a charged object, which can affect the distribution of the electric field and the resulting shape and size change of the sphere. This differs from other forms of field evaporation, which typically involve applying an electric field to a neutral object.

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