We think of the water that comes out of our taps as H20, but there’s more swirling around in there than hydrogen and oxygen atoms. There are also loads of ions - charged particles that the water molecules pick up during its travels through different environments like pipes and soil. Tiny amounts of substances like iron, chlorine, and sodium. Even water that’s been distilled has ions. Those ions are perfectly healthy for us to drink, but all of those positive and negative charges can interfere with the operation of the magnet.
Some of the ions in the water have a positive charge and are called cations. The rest have a negative charge and are called anions. The resin beads also hold a positive or negative charge and attract the ions with the opposite charge. This process leaves the water ion-free and ready to cool off our magnets.
We go through quite a lot of deionized water at the MagLab. Some 400 liters a second are required to keep just one – our 45 tesla hybrid – of our many magnets running at the right temperature. Cool!