Ice-Z-hot conditions

Researcher Daniel Dolan used Sandia's Z Machine to compress water into ice at extreme temperatures and pressures.

Sandia National Laboratory's huge Z machine, capable of generating temperatures hotter than the Sun, also turns water into ice — in nanoseconds. The ice, however, is hotter than boiling water. The three commonly known phases of water (ice, liquid, and vapor) are only a small part of water's repertoire of states, says Sandia researcher Daniel Dolan.

Compressing water normally heats it, but under extreme compression, water more easily enters the ice phase than remain in the more energetic water phase. In the Z experiment, the volume of water shrank abruptly and discontinuously, consistent with the formation of almost every known form of ice except the ordinary kind, which expands. (There are at least 11 other known forms of ice occurring at a variety of temperatures and pressures.) The 20 million-A electrical pulses the accelerator sends through water compress the liquid, which acts as an insulator and as a switch.

The Z machine is being refurbished with even more powerful equipment.