Warm dense matter

The term warm dense matter (WDM) comprises states of matter that are in the phase diagram in the region between plasmas and solids. The term was coined for those areas in which the density for models of plasma physics to high and the energy density is so high already that models are inaccurate for condensed matter.

Properties

The differentiation from other states of matter is not exactly defined. Often a temperature range of 5,000 K is indicated to 100,000 K, with pressures in the megabar range occur. But even at much higher temperatures up to several million Kelvin is still spoken of warm dense matter.

The term is not limited to a particular state of aggregation, but is also used for plasmas and compressed gases as for solids.

Occurrence and production

Warm dense matter exists in nature in the interior of massive celestial bodies such as stars and giant planets, where correspondingly high pressures and temperatures are predicted. Since these extreme conditions do not exist on the earth's surface is not warm dense matter of course and is not stable before, that is, for an extended period of time exist. To be able to conduct investigations, dynamic methods are employed, in which appropriate for very short periods of states created. Warm dense matter produced in the interaction of strong laser radiation or an ion beam with condensed matter. It is in any case to heating in general and to an expansion, that is, the density decreases. Through a particular structure of the target but can also be a compression can be achieved. Furthermore, gases and liquids can be compressed by using shock waves, it also results in heating. If the shock wave in this case strong enough produced warm dense matter. Light gas guns are frequently used for these experiments.

Importance

In the basic research warm dense matter is particularly in modeling the internal structure of giant planets such as Jupiter or Saturn of interest. Technical applications are mainly inertial confinement fusion and the development of nuclear weapons at their detonation especially in the first moments after ignition prevails warm dense matter. Experimentally, warm dense matter with the scattering of intense short-wave radiation, as it is created about the FLASH in Hamburg, are investigated.

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