Metal Surface Repels Electric Charges - Applications?

[sanman]

I came across this piece of news, about how researchers have found a way to repel electric charges away from a surface:

http://phys.org/news/2013-01-metal-surface-repel-electric.html

Metals are known for being good electrical conductors. Due to this property, a stationary electric point charge placed outside a metal will cause the electrons in the metal to redistribute in such a way that the point charge will always be attracted toward the metal surface. However, a new study shows that a metal surface will repel an electric charge packet moving parallel to it when the charge packet has a certain geometry and travels at a sufficiently high energy. It's not just metal surfaces that repel electric charges; any surface will repel this kind of charge packet since the repulsion is caused by the properties of the packet, not the surface. The counterintuitive phenomenon could have implications for improving particle accelerator experiments.

I was thinking that perhaps it could be useful for more than just particle accelerator experiments. Could it be used to improve Electric Propulsion of spacecraft ? If so, then in what ways?

The results not only add to scientists' understanding of fundamental electrodynamics, but could also prove useful for designing particle accelerator experiments. When a high-energy charge gets close to the surface of an accelerator wall, it produces transverse and longitudinal wakefields that can negatively affect the beam properties. Ribič predicts that manipulating the packet geometry may help alleviate this effect.

In the future, Ribič hopes that further investigations into the largely neglected effects of charge geometry will have even greater fundamental and practical consequences.

"We will probably also check what happens with other geometries," he said. "One interesting example would be a ring of charge with a large radius. For an infinitely large ring, one should also get repulsion between a ring that is placed into a guiding tube of an accelerator. Then the question is how the ring and tube radius affect the interaction. We are also planning to explore the interaction between charges and anisotropic media (such as uniaxial dielectrics)."

So this appears to be an area which hasn't gotten much attention before, and so I'm thinking that it might result in new improvements that haven't been previously considered or attempted.

How could this be used to improve an ion drive, for example? Can it help to improve beam collimation, and reduce grid erosion? Can it improve performance?

What other things could it improve besides spacecraft propulsion?

 

[mfb]

Ion drives are basically small particle accelerators.

I am bit sceptical concerning applications in particle accelerators. The usual bunch geometry is long in the direction of motion (for a lower charge density and other things) and narrow in the other two (to reduce the required beam pipe diameter), exactly the opposite of the geometry described there.