Plasma
Also called: Fourth state of matter · Topic: Energy Resources of India: Conventional and Non-conventional · NCERT: Beyond NCERT
Meaning
Plasma is often called the fourth state of matter. The other three are solid, liquid and gas. Plasma forms when a gas gets so hot that its atoms lose their electrons. What is left is a mix of free electrons and charged nuclei (the centres of the atoms). Because these particles carry an electric charge, magnetic fields can push and steer them. This matters for nuclear fusion, where light nuclei join together and release energy. Fusion needs plasma hotter than the core of the Sun. No material on Earth can hold anything that hot, so the plasma has to be held by magnets. If it touches a wall, it cools down and picks up impurities.
Example
India's Institute for Plasma Research in Gandhinagar, Gujarat, runs tokamaks such as ADITYA and SST-1. A tokamak is a ring-shaped vacuum chamber that uses magnets to hold hot plasma away from its walls. ITER in France is the world's best-known fusion project, and India is a partner. ITER uses the same tokamak design, with deuterium and tritium (two forms of hydrogen) as fuel.
Don't confuse with
- Gas: an ordinary gas is made of whole atoms with no overall charge, so magnets cannot steer it. In plasma, the atoms have lost their electrons, so the particles are charged.
- Blood plasma: this is the pale liquid part of blood that carries blood cells. It has nothing to do with the hot, charged state of matter.