Ok kiddo, imagine you have a glass of water. You know that if you heat that water, it will turn into steam, right? Now, imagine that you have a pot with some water and you want to heat it up to make steam, but you don’t want to lose any water. A smart solution would be to trap the steam you make in the pot so that it can’t escape.
This is what happens in a saturation dome: it’s like a lid that sits on top of a pot, but instead of trapping steam in a pot, it traps steam in a container called a boiler.
The steam is formed by heating water in the boiler, but instead of escaping into the air, it stays inside the boiler thanks to the saturation dome. The boiling water and steam inside the boiler have a specific pressure and temperature at which the steam is said to be “saturated” or fully “saturated” with water.
This saturation point is where the steam contains as much water as it can hold without any of the water droplets falling out of the steam. And, the saturation dome helps to keep the steam in this point of saturation. That’s why it’s called a saturation dome.
So, in short: a saturation dome is like a lid for a pot that keeps steam in a container called a boiler, and helps maintain a specific temperature and pressure where the steam is fully saturated with water.