Heliumkärnor

Heliumkärnor, also known as alpha particles, are a type of atomic nucleus consisting of two protons and two neutrons. This specific arrangement makes them identical to the nucleus of a helium-4 atom, hence the name. They are a classic example of a tightly bound nuclear cluster and are positively charged due to the two protons.

These nuclei are most famously emitted during a process called alpha decay, a form of radioactive decay exhibited by some heavy, unstable elements like uranium and radium. During alpha decay, a parent nucleus spontaneously transforms into a daughter nucleus by ejecting a heliumkärna to achieve greater stability.

Due to their relatively large mass and double positive charge, helium nuclei have a low penetrating power. They can be stopped by a sheet of paper or even a few centimeters of air. However, they can cause significant ionization damage to living tissue if alpha-emitting substances are ingested or inhaled.

Beyond radioactive decay, heliumkärnor play a fundamental role in nuclear fusion. In stars, including our sun, the fusion of hydrogen nuclei eventually leads to the creation of helium nuclei. This process releases enormous amounts of energy. In experimental fusion reactors on Earth, achieving the fusion of deuterium and tritium to form a heliumkärna is a primary goal, as it is a key reaction for potential future power generation.