eli5: once we are able to sustain a fusion reaction, it is supposed to be a self sustaining process (so I have read). How would we be able to “switch off ” this process, and wouldn’t a self sustaining process be an example of a perpetual process?

Question

eli5: once we are able to sustain a fusion reaction, it is supposed to be a self sustaining process (so I have read). How would we be able to “switch off ” this process, and wouldn’t a self sustaining process be an example of a perpetual process?

In: 4

Answer 1

A self-sustaining process taken literally, would be “perpetual motion”. In practice, it is a reaction which will continue until it runs out of reactants or is somehow interrupted.

A car engine requires the starter motor to get going, but once started it is “self-sustaining” until you turn it off.