Unlike nuclear reactions, nuclear reactions are not affected by changes in temperature,
pressure, of the presence of catalysts. Also nuclear reactions of given radioisotope cannot be slowed down, speeded up, or stopped.
I think the best word here would be compress. It is to compress that is defined as to squeeze a gas into a smaller space. Compression is the reduction of volume which cause an increase in pressure of the gas. Hope this answers the question. Have a nice day.