Watch the ions if you want to know how the plasma performs inside your tokamak. Due to reactions with other ions or neutrals, some of the ions inside the ultra-hot plasma soup strip off their charge. These neutral particles do not respond to the magnetic cage of the tokamak and escape. Installed in one of the equatorial ports of the ITER machine, a Neutral Particle Analyzer (NPA) will catch these escaping particles and measure their energy and mass. A few calculations later and scientists will glean knowledge on the confinement of ions inside of the plasma and the efficiency of heating and fuelling. Essential knowledge on the way to Q≥10.