On the possibility of the ITER machine to reach ignition

Summary form only given. The present analysis of ITER is based on the known parameters for its operation, i.e., temperature 20 kV decreasing linearly from the center towards the plasma periphery; magnetic field profile: 5 Tesla decreasing towards the plasma periphery with a known relation; particle density: 10/sup 14/ cm/sup -3/; major radius: 8m; minor radius: 4m. It is assumed that 400 MW of power input are required to bring it toward ignition, and that the reactor works with an efficiency of 30% of conversion energy into electricity. On the basis of the above data and assumptions, it is found that the heat loss from the entire plasma is /spl sim/5/spl times/10/sup 8/ watts. Moreover, it is found that the temperature of the first wall is 40 eV for an energy transfer efficiency a=13.1%, or 60 eV for a=37.5%. When one integrates over the entire volume of the plasma the energy balance, i.e., energy produced by neutrons and alpha particles, and losses by bremsstrahlung and heat, one finds that the machine cannot reach ignition.