Warm dense matter
The term warm dense matter (WDM). warm dense matter , includes states of matter that are in the phase diagram in the area between hot plasmas and condensed matter . The term was coined for those areas in which the density for models of plasma physics is too high and the energy density is already so high that models for condensed matter are imprecise.
properties
The area of warm dense matter is characterized by the fact that it is a plasma in which quantum and strong correlation effects prevail. This area can therefore be found in the phase diagram where the thermal energy is in the area of the Fermi energy and the kinetic energy is comparable to the Coulomb potential (i.e. degeneracy parameter θ ≈ 1 and coupling parameter Γ ≈ 1).
The demarcation from other states of matter is not exactly defined. A temperature range of 5,000 K to 100,000 K is often specified, with pressures in the megabar range. But even at significantly higher temperatures up to several million Kelvin, one speaks of warm, dense matter.
Occurrence and production
In nature, warm, dense matter exists in the interior of massive celestial bodies, such as stars and large planets , in which correspondingly high pressures and temperatures are predicted.
Since these extreme conditions do not exist on the earth's surface, warm dense matter does not exist naturally here and cannot be stable, i.e. H. exist over a longer period of time. In order to still be able to carry out investigations, dynamic methods are used in which corresponding states are created for very short periods of time.
Warm, dense matter is created by the interaction of strong laser radiation or an ion beam with condensed matter. In any case, there is a heating and, in general, an expansion , i. H. the density decreases. However, compression can also be achieved through a specific structure of the target .
Furthermore, gases and liquids can be compressed with the help of shock waves , which also leads to heating. If the shock wave is strong enough, warm, dense matter is created. Light gas cannons are often used for these experiments .
meaning
In basic research , warm, dense matter is of particular interest when modeling the internal structure of gas planets such as Jupiter or Saturn .
Technical applications are mainly inertial fusion and the development of nuclear weapons , when detonated, especially in the first moments after ignition, warm, dense matter predominates.
Warm, dense matter with the scattering of intense short-wave radiation, such as that generated at FLASH in Hamburg, can be examined experimentally.
Individual evidence
- ^ Frontiers and Challenges in Warm Dense Matter | Frank Graziani | Jumper . ( springer.com [accessed July 9, 2016]).
- ↑ a b Frank Grotelüschen: Warm, dense, extreme - researchers take a close look at the new state of matter. Deutschlandradio, April 12, 2011, accessed on January 26, 2012 .
- ↑ Warm Dense Matter. University of Florida, accessed February 8, 2012 .
- ↑ a b Inside Jupiter and Saturn. University of Jena, July 26, 2007, accessed on January 26, 2012 (press release).
- ↑ Warm Dense Matter. (No longer available online.) GSI Darmstadt, December 4, 2009, archived from the original on September 3, 2011 ; Retrieved February 16, 2012 .