Neutron calibration techniques for comparison of tokamak results

TL;DR: In this article, the in situ calibration was performed by moving the 252Cf neutron source toroidally through the JT•60 vacuum vessel, and the total detection efficiency for the torus neutron source was obtained by averaging the point efficiencies over the whole toroidal angle.

TL;DR: A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ∼5 × 10(9) counts/s.

Abstract: The deuterium operation of the large helical device (LHD) heliotron started in March 7, 2017, after long-term preparation and commissioning works necessary to execute the deuterium experiment. A comprehensive set of neutron diagnostics was implemented to accelerate energetic-particle physics research in the LHD. The calibrated ex-vessel neutron flux monitor indicated that the total neutron emission rate in the first deuterium campaign reached 3.3 × 1015 n s−1 in inward shifted magnetic field configuration where confinement of helically trapped energetic ions is predicted to be better. Density dependence of measured total neutron emission rate was consistent with that predicted by the calculation. The neutron decay rate analysis following perpendicular deuterium beam blips injection suggested that the confinement of helically trapped beam ions can be understood by the classical slowing down model in relatively high-electron density plasmas at inward shifted magnetic field configuration. On the other hand, loss of helically-trapped beam ions was recognized even in the inward shifted configuration in the case of low density. Performance of the vertical neutron camera was verified by changing the plasma position and/or magnetic field strength. Drastic change of neutron emission profile was observed when the resistive interchange mode driven by helically-trapped beam ions appears. It was successfully demonstrated that the vertical neutron camera can play an important role in revealing radial transport and/or loss of beam ions. Triton burnup study was also conducted. In the first deuterium campaign, the maximum triton burnup ratio of 0.45% was obtained in inward shifted configuration. The burnup ratio decreased as a plasma was shifted outwardly as expected.

TL;DR: In this paper, the authors present a detailed and realistic 360° MCNP model of the ITER tokamak called E-lite, which solves previously intractable problems with marked benefits for the future nuclear analysis of ITER, with applications to DEMO and future reactors.

TL;DR: Using indium activation foils, the toroidal and poloidal neutron emission patterns for PLT plasmas which include ICRF and neutral beam heating were determined by counting the 336 keV γ-line of the 115mIn decay as discussed by the authors.

TL;DR: In this paper, both D-D and D-T neutrons were used to calibrate the TFTR neutron activation (NA) system for point sources located within the tokamak.

TL;DR: In this paper, the primary TFTR neutron source strength measurement system consists of seven fission detectors previously calibrated with D-D and D-T neutron generators and a 252Cf neutron source inside the TFTR vacuum vessel.

TL;DR: Alcator C operations commenced with discharge cleaning and tokamak operation using hydrogen filling gas as discussed by the authors, which resulted in dosimeter readings of a few roentgen per shot in the vicinity of the limiter and a localized source of neutron emission of up to 109 neutrons per shot which were subsequently identified as having photonuclear origin.