Extremely unlikely, but possible.

First, you have to find a free electron somewhere in the air. There are always few of them.

Next, it needs some luck to accelerate all the way from one electrode to the other without hitting some air molecule and wasting its energy. Still possible.

If you accelerate a single electron over 1100 kV and smash it on some matter, you have quite low, but still measurable chance of hitting a nucleus directly. Hitting an electron is not going to work - the other electron will recoil with the ~half of the energy.

Next it has to kick a virtual positron out of virtuality and into existence. It has barely the needed energy and almost no energy budget left to spend on different non-idealities. But possible.

I am too lazy to do a "fermi approximation", but I have a gut feeling that having a good detector and great deal of time, you may get a positron or two.


You are right that lightnings produce positrons roughly the same way. Then again, they try harder, use more resources and were still just recently caught producing positrons.