If I get excess heat, what is the best gas to use to kill the excess heat without permanently ruining the chances of getting excess heat again (I would not do that until I've collected a lot of data with D2)?
Helium?
Is nitrogen a bad choice because it would somehow permanently bond with the nickel or palladium and ruin future chances of getting excess heat with D2?
I think air would be a bad choice because that would form metal oxides (that may or may not be removed with D2).