In seeking to achieve fusion energy, research on magnetic field confinement of high-temperature plasma is being conducted around the world. In a high-temperature plasma, there is a temperature gradient. When the temperature gradient becomes steep, turbulence is generated. Because the high-temperature regions and the low temperature areas are mixed due to the turbulence, the core temperature cannot be effectively raised. Thus, research on the generation and suppression of turbulence is being performed around the world on experimental devices of magnetically confined plasma (tokamaks and helical devices). It has been very difficult to distinguish where and how turbulence propagates in a plasma. Researchers have predicted that turbulence expands into other regions, a phenomenon called “turbulence propagation,” but this has not been observed experimentally.