Divertor Neutron Flux Monitor: Conceptual Design and Calibration

The operating conditions of a neutron diagnostic systems which are responsible for measuring of the total neutron yield in the ITER tokamak reactor are analyzed. Based on results of neutronic calculations and analysis of suitable methods for measuring the neutron yield, a concept of a system for neutron flux measurement in the divertor is proposed. The design for the neutron flux monitor located in the divertor cassette of the tokamak is selected in view of the requirements specified for the neutron diagnostic system of the ITER and its operating conditions. Several fission chambers with different sensitivities and radiator materials will be used for measurements. System is capable of neutron fluxes measuring over the entire dynamic range of the ITER neutron yield with an error of {delta}<10% and a time resolution of 1 ms that are necessary for studying the physical phenomena of ignition and burning plasma. The problems of carrying out of the divertor neutron monitor efficiency calibration with the aim to measure the absolute value of the neutron yield in the ITER tokamak reactor are also discussed.