The Electric Arc Shock Tunnel (EAST) at NASA Ames can generate hypervelocity shockwaves in test atmospheres to understand what happens during atmospheric entry. This system uses a capacitor bank that stored up to 1.25MegaJoules to drive a shockwave in a test gas then observe the light emitted.
This is essential to determining the radiative heating that will be experienced during atmospheric entry, and the facility at NASA Ames is the only one in the world that can even get close to the conditions experienced by probes to the gas giants.
Credit to : Scott Manley