Dusty plasmas are ionized gases containing small particles of solid matter. These particles become electrically charged. Often their charges are very large, so that they repel one another strongly. These charged particles can be suspended in a plasma, levitated against gravity by any modest electric fields that might be present in the plasma.

Not everyone uses the phrase "dusty plasma." In some countries, it is common to use a different term:

• dusty plasmas
• complex plasmas
• fine particle plasmas
• colloidal plasmas

Who cares about dusty plasmas?

This is a highly interdisciplinary topic, drawing interest in the fields of plasma physics, condensed matter physics, semiconductor technology, astrophysics, and other areas as well.

Within the field of plasma physics, interest arises from experimenters in both basic plasma physics and in the applied area of fusion energy research.

Condensed matter and plasmas have common physics when the plasma is "strongly-coupled," which means that interparticle potential energies are greater than particle kinetic energies. Under these conditions, charged particles in plasma self-organize in structures that resemble, at a microscopic scale, the structures of crystalline lattices or liquids. There are several experimental ways of making strongly-coupled plasmas -- due to the large particle charge, dusty plasmas are perhaps the easiest kind of strongly-coupled plasma to form, and the easiest to diagnose as well. The term "plasma crystal" is sometimes used for these kinds of experiments.

In semiconductor manufacturing, particulates can grow either by flaking from vacuum vessel walls or by nucleation in the gas phase -- either way, they represent a contamination problem when manufacturing wafers or masks.

Astrophysics was the original area of research of dusty plasmas. Interstellar clouds, planetary rings, and comet tails are examples of natural dusty plasmas. In astrophysics, small particles of solid matter, as seen in telescope images as dark clouds, are called "dust."That is how the term "dusty plasmas" originated.

How can I learn just a little more?

A more detailed introduction to the topic of dusty plasmas, intended for general physics readers, can be found in a review paper that Bob Merlino and John Goree wrote for Physics Today: