The neon-burning process is a set of nuclear fusion reactions that take place in evolved massive stars with at least 8 Solar masses.
At such high temperatures photodisintegration becomes a significant effect, so some neon nuclei decompose, absorbing 4.73 MeV and releasing alpha particles.
[1] This free helium nucleus can then fuse with neon to produce magnesium, releasing 9.316 MeV.
After a few years the star consumes all its neon and the core ceases producing fusion energy and contracts.
Again, gravitational pressure takes over and compresses the central core, increasing its density and temperature until the oxygen-burning process can start.