If I have a volume of gas in a sealed container with a special one way valve in it, and I heat the gas inside the container, the pressure increases and some gas escapes through the valve to the outside. I now have less atoms of gas inside the container, which, when cooled back to the starting temperature will be a partial vacuum. If I continue to heat the gas in the container higher and higher, what is the maximum equivalent vacuum that I could obtain? Is the limit going to be the maximum temperature I can obtain in the gas? Or some other physical limit? With enough power to create sufficient heat, could I in effect reach a state, for example, of 10 -6 torr, as far as the number of atoms in the volume and at the same time be maintaining an internal pressure equivalent to the pressure outside the container? So to avoid 'practicalities' of the valve, let's say it works on effusion or in some ideal way that would not let any molecules back into the chamber and that the chamber material and construction is some ideal container that can withstand any temperature and doesn't pass any heat through it's walls to the outside so there is no loss of heat there.