This is a view of an electric arc using an apparatus of William Gurstelle.

 

 

Can an electric arc jump a vacuum gap?

This is a view of an electric arc using an apparatus of William Gurstelle.

 

 

Can an electric arc jump a vacuum gap?

Yes. Arcing was a problem with our ion optics in the experiment I worked on at TRIUMF. It limited the voltage you could apply. Fortunately, the arcing tends to destroy the tiny protrusions that enable it in such devices, so you can "condition" a device to withstand higher values over time.

What colour is an electric arc through a vacuum?

What colour is an electric arc through a vacuum?

I don't recall seeing them. They would, of course, give off x-rays, as tends to happen when you slam a many kV electron into a surface.

Does lightning hitting a structural lightning conductor generate x-rays?

This is a view of an electric arc using an apparatus of William Gurstelle.

 

Can an electric arc jump a vacuum gap?

No

From

http://en.wikipedia.org/wiki/Electric_arc

"An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current through normally nonconductive media such as air."

No gas: no arc.

 

You can get discharges in low pressure systems, but not in a strict vacuum.

I don't think a fairly good vacuum would carry enough current to heat the electrodes far enough to get significant thermionic emission.

As I understand it, I see no conflict here. There is merely a difference in defining the circumstances of what the arc is, whether it be a flow through a gas or a flow of electrode material in a vacuum. For the benefit of those to follow, correct me if I'm wrong.

 

I was led to the following on seeking further explanations. http://en.wikipedia.org/wiki/Paschen's_law

http://en.wikipedia.org/wiki/Spark_gap

"It is impossible for a visible spark to form in a vacuum. Without intervening matter capable of electromagnetic transitions, the spark will be invisible (see vacuum arc)"

(emphasis added)

 

http://en.wikipedia.org/wiki/Vacuum_arc

"A vacuum arc can arise when the surfaces of metal electrodes in contact with a good vacuum begin to emit electrons either through heating (thermionic emission) or via an electric field that is sufficient to cause field electron emission."

The article at Wiki was very presomptuous!

 

Vacuum discharge (which you may call arc or not, I don't care) is known to occur at fields that can't possibly create field emission, and at electrode temperature (even locally) that makes thermoionic emission impossible. In fact, it's still a mystery, and the subject of research.

 

And by the way, vacuum discharge is not just a faint glow, it's an authentic zap.