Fusion plasma is a state of matter consisting of a hot, ionized gas made up of positively charged nuclei (ions) and free electrons. It is the medium in which nuclear fusion —the process that powers the sun and stars—takes place. Key Points: What is Plasma? Plasma is the fourth state of matter, formed when a gas is heated to such high temperatures that atoms become ionized (electrons are stripped from nuclei). Role in Fusion: In fusion reactors, such as tokamaks or stellarators , plasma is heated to extremely high temperatures (over 100 million degrees Celsius) so that atomic nuclei have enough energy to overcome their repulsive forces and fuse together, releasing large amounts of energy. Why is it Important? Fusion plasma is essential for achieving sustainable nuclear fusion , a potentially limitless and clean energy source, with minimal radioactive waste and no greenhouse gas emissions. Challenges: Containing and controlling such high-temperature plasma is technically difficult. Methods like magnetic confinement (e.g., using powerful magnets) and inertial confinement (e.g., using lasers) are used to achieve this.