The helium nucleus carries an electric charge which will be subject to the magnetic fields of the tokamak and remain confined within the plasma, contributing to its continued heating. However, approximately 80 percent of the energy produced is carried away from the plasma by the neutron which has no electrical charge and is therefore unaffected by magnetic fields. The neutrons will be absorbed by the surrounding walls of the tokamak, where their kinetic energy will be transferred to the walls as heat.
In ITER, this heat will be captured by cooling water circulating in the vessel walls and eventually dispersed through cooling towers. In the type of fusion power plant envisaged for the second half of this century, the heat will be used to produce steam and by way of turbines and alternators electricity.
In terms of sheer scale, the energy potential of the fusion reaction is superior to all other energy sources that we know on Earth. Fusing atoms together in a controlled way releases nearly four million times more energy than a chemical reaction such as the burning of coal, oil or gas and four times more than nuclear fission.
from https://www.iter.org/sci/Makin...