Experimental dynamos: from models to applications to the geodynamo

Larmor proposed in 1919 an explanation for the origin of the Sun’s magnetic field. This phenomenon, known as the dynamo effect, is considered to be responsible for most of the magnetic fields of astrophysical objects, including that of the Earth. It took over 80 years after Larmor’s explanation for the first laboratory experiments to demonstrate the dynamo instability. After a brief introduction to the three experiments that have managed to observe this effect, I will describe what they have taught us about the possible regimes of dynamos of planets and stars, especially regarding the geodynamo.