Quasi‐Isentropic Plane Compression of Matter at Megabar Pressures by Using a Layered System to Diminish First Shock Wave Intensity

The most dense states are generated dynamically under isentropic compression. This method is convenient to detect phase transition and allows overview of full states from zero to highest achievable pressure in one shot. The main increase of entropy in multiple shock compression process is due to the intensity of first shock in the investigated matter. The diminishing of this shock and the absence of strong shocks following it gives an opportunity to approach isentropic compression. A layered system consisting of polystyrene foam and steel layer was used to approach a compression path of nitrogen close to isentropic. Projectile acceleration in the helium atmosphere with proper initial gas density with common explosive plane shock wave generator was also used to create a quasi‐isentropic compression path. The computer modeling and experimental verification of the method was made.