We often refer to the "magic" of our vacuum tubes, but make no mistake, it is pure and simple science! Between the vacuum tube's two layers of glass is a layer of... nothing! That's right, nearly all of the air has been removed, preventing any convection or radiation of the heat from one layer to the other. Without a thermal bridge to move the heat, the tubes external face remains cool while the internal tube can hit temperatures in excess of 550°F/280°C
Pretty cool right?!