When two or more than two light nuclei are brought to the range of 10-10 m distance fusion can take place. But, it is not possible to bring lighter particle within this range in normal stage due to strong electrostatic force of repulsion. The nuclei can be brought to 10-10 m range by using very high tempt (about 107 K ) . Infect at this temperature every substance metal so, the nucleus of different atoms remains in ionized state known as plasma state. At this condition, in order to prevent these particles (in plasma state) , to come the contact of particles with wall of the container strong magnetic field is applied around the container. When the particles come in range of 10-10 m, slowly the tempt reduces and is deposited at the container which is a fusion state of different nuclei.