thermonuclear

Thermonuclear refers to processes that involve nuclear reactions at extremely high temperatures. The term is most commonly used to describe fusion reactions in which light atomic nuclei collide at sufficient energy to overcome electrostatic repulsion and fuse into heavier elements. Fusion releases large amounts of energy per reaction compared to chemical reactions.

In astrophysics, thermonuclear fusion powers stars. Core temperatures reach tens of millions of kelvin, enabling reactions such as the proton–proton chain and the CNO cycle, converting hydrogen into helium and emitting energy and neutrinos. Conditions are provided by gravity compressing stellar matter.

In weapons technology, thermonuclear refers to staged fusion devices, often called hydrogen bombs, that use a fission primary to create the heat and pressure needed to drive a secondary fusion stage. The design, associated with Edward Teller and colleagues, achieves much higher yields than fission alone. Discussions about policy, arms control, and nonproliferation accompany thermonuclear weapons.

In energy research, thermonuclear fusion holds the promise of a nearly inexhaustible and low-radioactivity energy source. Efforts pursue magnetic confinement (tokamaks and stellarators) and inertial confinement (laser-driven capsules). The aim is to reach breakeven or net energy gain, where more energy is produced than consumed. Projects include the ITER tokamak and the NIF laser facility, both international collaborations.

Despite progress, sustained net energy gain and practical commercial reactors remain under development, with technical challenges involving plasma confinement, material endurance, and energy capture. Thermonuclear fusion remains a central area of high-energy physics and future energy strategy.