[SIZE=+1]On our planet, we inhabit a calm little oasis of ordinary solids, liquids and gases that is immersed in a perpetually blowing, roiling, flaring erupting substance of a very different kind, called plasma. Sometimes called the fundamental state of matter to distinguish it from its tamer cousins, plasma makes up more than 99 percent of the visible universe. The plasma side of the cosmic ledger includes the seething atmospheres and interiors of stars, the wind of particles that our sun flings outward into space, EarthÕs cocoon-like magnetosphere, the tenuous wasteland between stars and galaxies, and fantastically energetic displays such as quasars, supernovas and parts of the compact spinning stars that spray out beams of x-rays like some kind of hellish fire hose. [/SIZE]
[SIZE=+1]When they are artificially produced and bottled up here on Earth, plasmas turn out to be extremely useful. We create plasmas each time we flip on a fluorescent light or a neon sign. Plasmas etch the tiniest circuit features on the microprocessor chips that are at the heart of our desktop computers. Carefully controlled clouds of plasma can "rain", or deposit, thin layers of materials onto surfaces as a crucial step in manufacturing industrial diamonds and superconducting films. Particle accelerators much more compact and powerful than any now in existence could emerge from experiments that are using intense plasma waves to push electrons up to relativistic speeds. Jets of plasma spin and maneuver orbiting satellites. Even without leaving EarthÕs surface, however, laboratory experiments can shed light on the wider universe of plasma phenomena, as when the shock waves produced by laser beams striking a small spec of plasma help unravel the dynamics of an exploding star. [/SIZE]
[SIZE=+1]But no matter how cleverly we try to harness them, plasma sometimes revert to their unruly nature: Only after decades of research have physicists learned, by fits and starts, how to confine a plasma that is hotter than the sunÕs core, with the goal of producing large power plants using the same processes that causes the sun and stars to shineÐa phenomena called thermonuclear fusion. The long struggle to make a practical fusion devices partly reflects the challenge inherent in understanding plasma theoretically. Plasmas are so complexÑequally rich in physics and frustrationÑthat they often beggar all description, even by the most sophisticated theories and the most powerful supercomputers. (Adapted from James Glanz, The Pervasive State of Matter)[/SIZE]
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What is a Plasma?
Plasma is overwhemingly the dominant constituent of the universe as a whole. Yet most people are ignorant of plasmas. In daily life on the surface of planet Earth, perhaps the plasma to which people are most commonly exposed is the one that produces the cool efficient glow from fluorescent lights. Neither solid, nor liquid, nor gas, a plasma most closely resembles the latter, but unlike gases whose components are electrically neutral, plasma is composed of the building blocks of all matter: electrically charged particles at high energy.
Plasma is so energetic or "hot" that in space it consists soley of ions and electrons. It is only when plasma is cooled that the atoms or molecules that are so predominant in forming gases, liquids, and solids that we are so accustomed to on Earth, is possible. So, in space, plasma remains electrically charged. Thus plasmas carry electric currents and are more influenced by electromagnetic forces than by gravitational forces. Outside the Earth's atmosphere, the dominant form of matter is plasma, and "empty" space has been found to be quite "alive" with a constant flow of plasma.
Given its nature, the plasma state is characterized by a complexity that vastly exceeds that exhibited in the solid, liquid, and gaseous states. Correspondingly, the study of the physical and especially the electrodynamical properties of plasma forms one of the most far ranging and difficult research areas in physics today. From spiral galaxies to controlled fusion, this little-known state of matter, the fundamental state, is proving to be of ever greater significance in explaining the dynamics of the universe and in harnessing the material world for the greatest technological result.
Solids Condensed matter
Compact (nuclear) Liquids
&
Gases Fluid
(Navier-Stokes)**
Systems Plasmas Electromagnetic
(Maxwell-
Boltzmann)**
Systems *There are only four dominant naturally-occurring states of matter although many other states of matter exist when considered broadly (see A. Barton, States of Matter, States of Mind, IOP Press, 1997).
*The Navier-Stokes equations are basic equations for studies of fluids and neutral gas systems.
The Maxwell equations for electromagnetism and the plasma Boltzmann equation are the basic equations for studies of electromagnetic systems of which plasmas are a prime example
Courtesy of T. Eastman
