To design a practical fusion device of heavy hydrogen by the muon catalysis fusion reaction by applying a magnetic field to a normal temperature nuclear fusion reaction device due to the electrolysis of heavy water.

The normal temperature nuclear fusion reaction is made, for example, by applying a magnetic field B in parallel with the palladium cathode surface of an electrolysis device. As a result, a pion is generated at an electrical double layer on the cathode surface where positive ion and electron layers oppose each other, and a muneutrino beam ν is derived and advances straight through the inside of the cathode. At this time, positive ion beams of heavy hydrogen are implanted into the cathode surface and penetrate the inside of the cathode, a negative muon atom and further a negative muon molecule where an outer shell electron has been replaced by the negative muon are formed, which causes a nuclear fusion reaction to become helium. A magnetic field can be applied to the cathode for discharging heavy hydrogen and heavy hydrogen ion beams due to electron beams.