Question: Could a plasma window be used safely outside of a lab? If one could be used in the home, how would it change people's lives?

Susan Cartwright answered on 27 Apr 2020: last edited 27 Apr 2020 4:10 pm

The short answer is “no”. Plasma is ionised gas; that is, gas whose atoms have been ionised so that it consists of positively charged ions and negatively charged electrons. The usual way to convert a gas into a plasma is to eat it to extremely high temperatures – I think existing plasma windows run at about 15000 K. I do not want one of those in any of my windowframes, thank you very much. Also, the energy cost is huge: about 8000 W/cm.

More to the point, you don’t actually WANT the properties of a plasma window in an actual window. The key point about a plasma window is that it can hold pressure (that is, you can have a vacuum on one side and several atmospheres of pressure on the other), but it is transparent to radiation. This is very useful in a lab: you can generate a radiation beam in a vacuum (which is usually easier than doing so in an environment with pressure) and then pass it through the plasma window to do something on the other side. This feature is used in electron-beam welding for example: the beam is generated in a vacuum, but the things to be welded don’t have to be in a vacuum.

But this is not what you want to happen in your average domestic window. Even with double glazing, much of the heat in your house is lost through the windows – you want to make this more difficult, not easier! Likewise, you want the window in your oven door to keep the heat in, not spread it all over the kitchen.

So, overall, I don’t see any easy way to make plasma windows safe for use outside a lab, but I don’t really see any reason why you would want to do so anyway.