What is plasma?

About plasma—the state of matter,
not the blood component



"From the sun, there blows a wind so hot
that its atoms are split into electrically
charged particles, electrons, and ions."


Torsten Gustafsson, member of the Royal Swedish
Academy of Sciences

There are four states of matter, of which three are most familiar: solid, liquid, gas, with plasma being the fourth. Plasma is the highest-energy state with properties unlike those of the other states.

Plasma is best described as an ionized gas because it is made up of positively and negatively charged particles. That is, in a gas, the electrons are all bound to the nuclei of the neutral (no charge) atoms, but in plasma, the electrons are separated from the atom, which then becomes a positively charged ion.

Plasmas are by far the most common material in the visible universe, more than 99.9%. The Sun, most stars, and a significant portion of the entire interstellar medium are plasma. So plasmas play an important role in the universe and the creation of galaxies. Natural plasmas are uncommon in Earth conditions. The most notable plasma on Earth is lightning. Atmospheric gas is heated to a very high temperature and ionized by electrical currents. Another plasma we see is solar plasma flares, which interact with Earth’s electromagnetic field to create the Northern Lights (Aurora Borealis).

Interestingly, plasma-state matter received its name because chemist Irving Langmuir recognized that an electrified fluid carries electrons and ions in a similar manner to how blood plasma (the straw-colored liquid component of blood) carries red and white corpuscles in suspension. And, just as plasma makes up most of the matter in the universe, blood plasma makes up the majority of the body's total blood volume.

 Images of electron construction for the different types of plasma state such as solid, liquid, gas, and plasma.
Solid
 Images of electron construction for the different types of plasma state such as solid, liquid, gas, and plasma.
Liquid
 Images of electron construction for the different types of plasma state such as solid, liquid, gas, and plasma.
Gas
 Images of electron construction for the different types of plasma state such as solid, liquid, gas, and plasma.
Plasma

Applications of plasma

Man-made plasmas are commonly used in many areas of life:

  • Neon signs and fluorescent light bulbs, in which electricity strips the gas atoms of their electrons
  • Plasma-screen TVs
  • Plasma-arc welding, which permits faster welding speeds than gas welders, at lower cost than laser welding
  • Sterilization of heat-resistant medical instruments
  • Bactericidal in packaging of foodstuffs
 

Medical uses of plasma

Until recently, only the thermal properties of plasmas (temperatures >80°C) were utilized.

Ablation

Removal or excision of tissue (helium plasma)

Coagulation

Clotting of blood via plasma plume to control bleeding (argon plasma)

Surgical Incision

Separation of tissues by fine plasma 'scalpel' (argon plasma)

Cosmetics: Wrinkle
and Scar Removal

Thermally induced shedding of treated skin to reveal new skin underneath (nitrogen plasma)

Research now shows that plasmas also offer the possibility of targeting the application of therapeutic molecules. Plasmas are highly reactive and can interact with a broad range of cells and tissues to induce a similarly broad range of biological effects. Highly reactive molecules include argon, helium, hydrogen, nitrogen, and oxygen. Plasma also acts rapidly and penetrates the smallest openings and hollow spaces. Applications include hospital hygiene, the treatment of diverse skin and infectious diseases, and dentistry.

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