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What is plasma?

PlasmaPlasma consists of a gas heated to sufficiently high temperatures that the atoms ionize. The properties of the gas are controlled by electromagnetic forces among constituent ions and electrons, which results in a different type of behavior. Plasma is often considered the fourth state of matter (besides solid, liquid, and gas). Most of the matter in the Universe is in the plasma state. is a state of matter. Everything in the Universe is made of “stuff” called matter. All matter is made of atomsThe smallest particle of an element that exhibits the chemical properties of the element., and it can exist in different states. Many people are familiar with three states of matter: solid, liquid, and gas

Atoms are made of protonsA massive, positively charged elementary particle; one of the main constituents of the nucleus of an atom. A proton is 1836 times heavier than an electron., neutronsA subatomic particle with about the mass of a proton and no electric charge; one of the main constituents of an atomic nucleus; the union of a proton and an electron. A neutron is 1839 times heavier than an electron. and electronsA negatively charged elementary particle that normally resides outside (but is bound to) the nucleus of an atom.. Protons have a positive charge, neutrons have a neutral charge and they both make up the atom's nucleus. Electrons have a negative charge. They surround the nucleus of the atom.

In a solid, the atoms are tightly bound together. Solids have a fixed volume and shape. Heating up a solid will often cause it to change to a liquid. Liquids have atoms that are less tightly bonded together. They have a fixed volume, but not a fixed shape. Adding heat energy to a liquid will often transform it to a gas. Gasses have neither a fixed volume nor a fixed shape. Their atoms are not bonded together and they move around freely.

When heat energy is added to a gas, it begins to move around faster. When enough heat energy is added to a gas it can become a plasma.

Plasma is similar to gas, but its particles have a different structure and charge. Plasma forms when a gas becomes extremely hot. When this happens, the gas’ atoms gain lots of energy. This energy causes the electrons to detach from the nuclei of the gas’ atoms. When the negatively charged electrons detach, the positively charged protons and neutral particles called neutrons in the nuclei are left. These positively charged nuclei are called ions. When a gas is so hot that the electrons and protons split apart to form electrons and ions, we say that the gas has been ionized. Plasma is an ionized gas.

Plasma has some interesting properties because the particles are ionized. When charged particles move, as they do in a plasma, they create magnetic fieldsA field of force that is generated by electric currents. The Sun's average large-scale magnetic field, like that of the Earth, exhibits a north and a south pole linked by lines of magnetic force.. These magnetic fields can then cause the moving plasma particles to travel in certain directions and paths. The particles travel in spiraling paths like corkscrews.

To learn more about plasma, please visit the Windows to the Universe States of Matter web pages.

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Last Updated: 6 June 2014
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