Primarily carbon (atomic number 6), but there are some nuclear processes that yield nitrogen (7) and oxygen (8).
carbon
Nuclear Fusion.
In deuterium-tritium fusion, the result is helium-4. In helium fusion, carbon is produced.
Helium
Hydrogen undergoes nuclear fusion in the core of the sun to form helium.
Hydrogen undergoes nuclear fusion to form helium at a temperature of 107 K
Nuclear Fusion.
hydrogen fusion
On earth, for power production, the most likely fuel source will be hydrogen isotopes, not helium 3
In deuterium-tritium fusion, the result is helium-4. In helium fusion, carbon is produced.
Helium
Hydrogen undergoes nuclear fusion in the core of the sun to form helium.
Helium is produced by fusion in the interior of the Sun.
Hydrogen undergoes nuclear fusion to form helium at a temperature of 107 K
When hydrogen stocks run out
Nuclear fusion combines hydrogen atoms into helium atoms. Hydrogen is available from water and helium is an inert gas. When fusion reactors become technologically feasible, we will greatly reduce consumption of limited fossil fuels and production of greenhouse gases. Fusion reactors will not produce high level nuclear waste.
Helium originated from suns, where the fusion of hydrogen atoms forms the helium.
Helium