14/11/2023
Plasma Physics
Almost all of the observable matter in the universe is in the plasma state. Formed at high temperatures, plasmas consist of freely moving ions and free electrons. They are often called the “fourth state of matter” because their unique physical properties distinguish them from solids, liquids and gases.
Plasma densities and temperatures vary widely, from the cold gases of interstellar space to the extraordinarily hot, dense cores of stars and inside a detonating nuclear weapon. Plasma densities range from those in a high vacuum with only a few particles inside a volume of 1 cubic centimeter to 1,000 times the density of a solid.

Characteristics of typical plasmas.
NIF experiments are addressing two areas of plasma physics. First are studies of the phenomena created by laser beams interacting with plasma. Of particular importance are “stimulated Brillouin scattering” and “stimulated Raman scattering.” Both effects must be minimized to efficiently drive the implosion of the NIF fuel capsule in order to achieve ignition.
Mystery of Self-organization
The second area involves using NIF to emulate other plasma phenomena occurring in nature, such as interpenetrating plasmas. For example, one of the mysteries of astrophysics is how highly organized structures such as magnetic fields stretching millions of light years can emerge from the frenetic motion of plasmas. A team of Lawrence Livermore researchers has discovered that supersonic counter-streaming (directed at each other) plasmas created by powerful lasers give rise to “self-organized” electromagnetic fields similar to those found throughout the universe.
As revealed in proton radiography images, these electromagnetic structures are oriented perpendicular to the direction of the two plasma flows, have detailed features, and are much larger and persist much longer than would be predicted from the chaotic motions of the plasma ions and electrons.
Collisionless Shocks
Researchers are using NIF