ELISE testing rig will accelerate development of ITER heating

The rig, developed at the Max Planck Institute for Plasma Physics (IPP) near Munich, will aid the creation of a device that will heat the plasma in ITER, the fusion reactor currently taking shape in southern France, to temperatures hotter than the surface of the sun.

The ELISE (Extraction from a Large Ion Source) rig will test neutral particle injectors — devices that shoot fast, uncharged hydrogen atoms into fusion plasma. As they collide with particles in the plasma, they slow down, transfer their energy to the plasma, and cause its temperature to rise.

Neutral particle injection is one of the main ways that plasma in fusion reactors is heated: it has to reach a temperature of more than 100 million Kelvin in order for the charged hydrogen ions in the plasma to overcome electrostatic repulsion forces and come close enough together for fusion to occur.

ITER will be equipped with two neutral beam injectors, but as it is eight times the volume of the current largest fusion reactor — the UK-based JET (Joint European Torus) — the injectors will have to be larger and more powerful, pumping 16.5MW of heating power into 800m³ of plasma. Current injectors are ‘about the size of a dinner plate’, IPP said in a statement: ITER’s will have to be ‘about the size of a door’.