0000000000949783
AUTHOR
Jet-efda Contributors
Comparison of tritium measurement techniques for a laser cleaned JET tile
Abstract Over the last 7–8 years, two quantitative analyzing methods—accelerator mass spectrometry (AMS) and full combustion (FC) followed by scintillation detection have been applied for determining the tritium activity concentrations in JET divertor tiles. These methods have two main differences – the range of detection and the spatial resolution – and are thus complementary. However, these differences can also complicate the comparison of the two techniques for typical JET divertor samples. Therefore a cross comparison exercise for tritium measurements was performed between the two methods using specially produced identical standard samples. The cross comparison measurements were perform…
ITER-relevant calibration technique for soft x-ray spectrometer
The ITER-oriented JET research program brings new requirements for the low-Z impurity monitoring, in particular for the Be—the future main wall component of JET and ITER. Monitoring based on Bragg spectroscopy requires an absolute sensitivity calibration, which is challenging for large tokamaks. This paper describes both “component-by-component” and “continua” calibration methods used for the Be IV channel (75.9 Å) of the Bragg rotor spectrometer deployed on JET. The calibration techniques presented here rely on multiorder reflectivity calculations and measurements of continuum radiation emitted from helium plasmas. These offer excellent conditions for the absolute photon flux calibration d…
Improved EDGE2D-EIRENE simulations of JET ITER-like wall L-mode discharges utilising poloidal VUV/visible spectral emission profiles
A discrepancy in the divertor radiated powers between EDGE2D-EIRENE simulations, both with and without drifts, and JET-ILW experiments employing a set of NBI-heated L-mode discharges with step-wise density variation is investigated. Results from a VUV/visible poloidally scanning spectrometer are used together with bolometric measurements to determine the radiated power and its composition. The analysis shows the importance of D line radiation in contributing to the divertor radiated power, while contributions from D radiative recombination are smaller than expected. Simulations with W divertor plates underestimate the Be content in the divertor, since no allowance is made for Be previously …