Is it possible...

[Longranger]

To create an ionised path of light (whether negative or positively charged) at extremely high voltages?

[FilipŠebík]

As far as my knowledge goes, photons are neturally charged and they can ionize atoms but they can't be ionized. So to answer your question, No it can't.

But if you wanted to create a arc with very high voltages that illuminates surrounding area then it would work. But directing the path the arc will go is hard unless you use a glass tube that has electrodes on both ends and its filled by air. Someone would suggest glass tube filled (lol filled) with vacuum but that creates x-rays on very high voltages and can be dangerous.

[profdc9]

I'm not sure this is what you're after but "light bullets" have been used to direct Tesla Coil discharges...

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-20-12-12721

The article is not paywalled.

Dan

[Mads Barnkob]

The only things I have seen working are either to use a laser to make a pre-ionized channel in the air that the spark will prefer to travel in or to use a flame as the heated air will conduct better as-well.

[Hydron]

I'm not sure this is what you're after but "light bullets" have been used to direct Tesla Coil discharges...

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-20-12-12721

The article is not paywalled.

Dan

Wow, those guys had some really cool toys to play with. Their laser+control room was built into a full size shipping container!

[profdc9]

A while back I had thought perhaps a 405 nm laser could be used to ionize the air for this purpose, so I looked into it and found this paper, but I think the wavelength is too long.  These guys are using a Ti-sapphire regenerative amplifier that produces 1 mJ pulses.  I worked with Ti-sapphire regenerative amplifiers (however one that produced only uJ-energy pulses) but the energy of these pulses was too low for self-focusing.  Self-focusing occurs when the pulse intensity is high enough to alter the refractive index of the air so that it forms a gradient index lens that focuses the pulse and prevents it from spreading from diffraction.  The pulse can stay confined for a much longer distance than it ordinarily would from diffraction (the Rayleigh distance).  The peak power is sufficient to ionize the air as well.

Perhaps a tripled YAG (355 nm) or quadrupled YAG (266 nm) might work, but these are not cheap lasers!  Maybe one day...

Dan