No blablabla needed....
I did some additional research into EUV light.
It is absorbed by pretty much all matter, except certain layered materials which may be called meta-materials. Even these layered materials used in EUV lithographic systems are poor reflectors. Also, lithographic EUV must be done in a vacuum to prevent the EUV from heating or ionizing that atmosphere.
In simplest terms, the EUV spectrum is very energetic, can ionize almost any gas, and can heat both atmosphere and solid materials. In the SAFIRE reactor, Monty has mentioned how there is an instant thermal response because the EUV hits the walls of the chamber and is converted into heat before heat from the plasma can travel to the walls via convection. Obviously, some of the energy is absorbed by the atmosphere, but so much is produced some percentage can travel multiple feet, at least in the low pressure region in the SAFIRE reactor.