There are different states of matter in the earth: solid, liquid and gas. When energy is applied to a solid, it turns into a liquid, and a gas. When energy is added to a gas, it becomes a plasma. The fusion power generation we are aiming for is achieved by injecting hydrogen fuel into a high-temperature plasma of over 100 million degrees Celsius, where the injected hydrogen becomes high-temperature ions and causes a nuclear fusion reaction. The ionised hydrogen (fuel particles) are ejected out of the plasma over time, some being absorbed by the surface of the vacuum vessel wall, some bouncing off the wall and returning to the plasma, and some being ejected out of the vessel by a vacuum pump. This means that it is more difficult than expected to control the fuel particles in the way we want. This is why we are working to establish an easy and stable way to control the fuel particles.