Ganamae said:
hmm if the carbon freezing chamber would be located in the main structure, then what is the place they fight in then? do we know? a large fin in an empty space in the city doing what exactly?! measuring gas levels?

I find it odd that that little "boble" on the top of the fin houses the whole carbon chamber...

Well in Ralph McQuarrie's pre-production paintings there were originally 4 structures. Kind of like a set of processing plants. It actually makes sense that the carbon chamber would be located in these structures. Any waste gets dumped down the core and jettisoned out the same type of tubes that Luke is sucked into and to the planet below. After all it is a gaseous planet so doubtful anyone is living below. If you look at the carbon chamber it isn't actually that big. So it is plausible that it can be situated in the dome. The whole section where they fight by the window is like the main control room