Extreme water

Extreme water. Stars, nuclear explosions, and the early universe are three realms where matter exists in extreme conditions of pressure, temperature, and density. Over the past few decades, extreme matter has become increasingly accessible in the laboratory. (For an overview, see the article by Paul Drake in Physics Today, June 2010, page 28 .) Water is a favorite material to use because of its near incompressibility and its relevance to the interiors of giant planets, but taking water to the extreme has typically required about 100 kJ of energy per experiment. A team of physicists at the Technion–Israel Institute of Technology in Haifa has now generated extreme water on a smaller scale. By winding copper or aluminum wires around a ball and then dissolving the ball, the team created a spherical cage, as shown in the figure. The cage is connected to a pulse power generator with about 6 kJ of stored energy. When the wires are submersed in water and the stored energy suddenly released, the wires vaporize and produce strong shock waves that overlap to form a larger one that then converges on the sphere’s center. There, for less than a microsecond, the water is compressed sevenfold. Combining the experimental results with simulations, the researchers inferred that the water’s temperature reached nearly 10⁵ K at a pressure of 2 × 10⁷ atm. (O. Antonov et al., Phys. Plasmas 19, 102702, 2012.)