The importance of runaway electron (RE) detection, analysis of its parameters and suppression or mitigation is well recognized for large size tokamaks such as ITER. One of the wellestablished detection techniques is hard x-ray spectrometry that detects bremsstrahlung emission typically in the MeV range from the REs. It provides space, time and energy resolved measurements, which can also be utilized for the reconstruction of the RE energy distribution function. In this paper, forward modeling has been carried out for the detection of the confined REs and a numerical tool is developed. It calculates analytically anisotropic bremsstrahlung emissivity at each spatial position in the plasma in terms of several plasma, RE and geometrical parameters. The simulation provides line integrated energy resolved spectra of bremsstrahlung photons. The expected bremsstrahlung emission signal during plasma disruptions scenario as measured with the ITER hard x-ray monitor has been simulated for the first time aiming on optimizing the design parameters of this diagnostic. The possible dynamic range for the detection of confined REs is studied as well. The effect of the shape of the runaway distribution function in the momentum space on the observed diagnostic signal is also studied and briefly discussed.

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Neutronics aspects of a compact D-D neutron generator as a neutron source for the neutron calibration in magnetic confinement fusion devices are assessed by the MCNP calculation. The neutron emission distribution of the compact D-D neutron generator has a large anisotropy not only due to the scattering with the neutron generator body but also due to the intrinsic anisotropy of the differential cross-section of the d(d,n) 3 He reaction. The angular neutron distribution at the target of the compact D-D neutron generator is calculated with the PHITS code where the slowing down on the accelerated deuterons in the target material is considered. The calibration experiments are simulated by using the MCNP-6 code for the ITER neutron flux monitor (NFM) to be installed in the equatorial port. The detection efficiency of NFM is calculated for a D-D plasma neutron source, an idealistic D-D neutron source, a 252 Cf neutron source and the compact neutron generator. It is found that the detection efficiency of NFM for the compact neutron generator is approximately 50% larger than that for the idealistic D-D neutron source. The discrepancy is improved to be 25% by the intention of the target 20 cm from the body of the compact neutron generator.