It's not air pressure, it's a shock wave in liquid metal. The BBC article is simplified a bit too far for anyone with a technical background but I doubt if a

It's not air pressure, it's a shock wave in liquid metal. The BBC article is simplified a bit too far for anyone with a technical background but I doubt if a more accurate version would be much more meaningful to most people. There is a patent on it: https://patents.google.com/patent/US9424955B2/en https://patents.google.com/patent/US9424955B2/en ----Quote: 2. Description of the Related Art Various systems for heating and compressing plasmas to high temperatures and densities have been described. One approach for accomplishing plasma heating and compression by spherical focusing of a large amplitude acoustic pressure wave in a liquid medium is described in U.S. Patent Publica tion No. 2006/0198486, published Sep. 7, 2006, entitled “Pressure Wave Generator and Controller for Generating a Pressure Wave in a Fusion Reactor”, which is hereby incor porated by reference herein in its entirety. In certain embodi ments of this approach, a plurality of pistons is arranged around a substantially spherical vessel containing a liquid medium. A vortex or cavity is created in the liquid medium. The pistons are accelerated and strike the outer wall of the vessel generating an acoustic wave. The acoustic wave generated in the liquid medium converges and envelopes a plasma that is introduced into the Vortex, thereby heating and compressing the plasma. ----end quote