Physics · nuclei · NEET
The fuel must be heated to about 10^8 K (100 million kelvin). At that temperature the fuel becomes plasma. No solid material can touch plasma this hot without melting or vaporising, so holding the plasma in place is very hard. This confinement problem is the main reason a viable fusion reactor is still being developed.
About 10^8 K. Fusion needs two positive nuclei to come very close so the short-range nuclear force can bind them. But both are positive, so they push each other away by Coulomb repulsion. Only very high kinetic energy (very high temperature) lets them overcome this Coulomb barrier and fuse.
At 10^8 K the atoms lose their electrons. The fuel becomes a mix of free positive ions and free electrons. This charged gas is called plasma, the fourth state of matter. Because plasma is made of charged particles, it can be pushed and held by magnetic fields instead of solid walls.
Any solid container would melt long before reaching 10^8 K. Also, if the plasma touched a wall it would cool down instantly and fusion would stop. So the plasma must be kept away from all walls, usually by strong magnetic fields that trap the charged particles (magnetic confinement).
The Sun uses its enormous gravity to squeeze and confine the plasma, and it runs at about 1.5 x 10^7 K in the core. On Earth we have no such gravity, so we need even higher temperature (about 10^8 K) and we must confine the plasma using magnetic fields inside a device.
About 10^8 K (100 million kelvin), as stated in NCERT. This is higher than the Sun's core (about 1.5 x 10^7 K) because the reactor lacks the Sun's gravity to help confine the fuel.
Confining the plasma. At 10^8 K the fuel becomes plasma and no container can stand this heat, so the plasma must be held by magnetic fields away from all walls.
At such high temperature, electrons are stripped from atoms. The fuel becomes a mixture of positive ions and free electrons, which is called plasma.
Yes. NCERT notes that several countries including India are developing techniques for controlled thermonuclear fusion. If successful, fusion reactors could supply almost unlimited power.
The fuel (isotopes of hydrogen like deuterium) is abundant and it releases large energy with less long-lived radioactive waste than fission. If confinement is solved, it could give almost unlimited clean power.
