fusionsprocess

Fusionsprozess, or fusion process, refers to the combination of light atomic nuclei to form a heavier nucleus, releasing energy as a result of the mass defect. In nature this occurs in stars, where hydrogen isotopes fuse at extreme temperatures and pressures, powering stellar radiation. In human-made systems, scientists study controlled fusion as a potential source of large-scale, low-carbon energy.

In stars, the main pathways are proton-proton chains and, in more massive stars, the CNO cycle. These networks convert hydrogen into helium while emitting energy and, in some cases, neutrinos. The same energy production principle underpins laboratory fusion research, where the aim is to achieve sustained, net energy output.

Laboratory approaches to controllable fusion are primarily magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). MCF devices use strong magnetic fields to confine a hot plasma long enough for fusion reactions to occur. The most developed designs are tokamaks and stellarators. Heating methods include ohmic heating, neutral beam injection, and radiofrequency heating. ICF uses short, intense energy pulses to compress and heat small fuel pellets, condensing them to the conditions required for fusion.

Key conditions for fusion are extremely high temperatures, adequate particle density, and sufficient confinement time, collectively described by the Lawson criterion. The most common fuel mixture in experiments is deuterium-tritium, producing helium and a high-energy neutron. Achieving net energy gain (Q>1) remains a primary challenge, along with material durability under neutron flux, fuel supply, and reactor engineering.

As of today, fusion experiments have demonstrated substantial energy production but not sustained net-positive output. Major projects such as ITER and various national programs aim to reach practical, commercially viable fusion power in the coming decades.