Assessment of neutral particle analysis abilities to measure the plasma hydrogen isotope composition in ITER burning scenarios

Abstract

The main object of the neutral particle analysis (NPA) on ITER is to measure the hydrogen isotope composition of the plasma using measurements of the neutralized fluxes of the corresponding hydrogen ions. In burning scenarios the reliable on-line measurements of the tritium/deuterium (T/D) density ratio stands out as the most important application of the diagnostics. This paper presents the results of the error analysis of the NPA signals for 'official' ITER burning scenarios-inductive and steady state. The goal of the study is to find the range of values of T/D density ratio, where NPA measurements meet the ITER requirements specified for this parameter, i.e. 10% of accuracy and time resolution equal to 0.1 s. This analysis takes into account both the statistics of the particle counts detected by NPA and of the noise counts induced in NPA detectors by neutrons and gammas. The calibration errors and errors of the external plasma parameters, used in the interpretation of NPA data, are also accounted. The results of the study for low (20-200 keV) and high (200 keV-2 MeV) energy ranges of the D and T neutral fluxes are discussed. It was shown that in the inductive scenario NPA can provide the required accuracy of the T/D density ratio measurement if the plasma composition varies within 0.2-10 (edge measurements) and 0.15-10 (core measurements). In the steady-state scenario these ranges are 0.01-10 (edge measurements) and 0.07-7 (core measurements).

Measurements of the radial profile of the plasma isotopic composition in JET plasmas using Alfvén eigenmodes

“…Fuel retention in the plasma walls and radial transport of different isotopes are between the main problems that need to be addressed to obtain reliable high-performance operation in tokamaks, particularly when an optimal mixture of deuterium and tritium is intended to be used to produce plasma regimes that aim to achieve a high fusion energy gain [7,8]. Currently, a combination of a low-energy NPA working as an isotope separator and a high-energy NPA [9] is foreseen as the main diagnostic tool for the measurement of the hydrogen isotope composition in ITER [10]. The main advantage of this technique is that it measures the flux of neutrals exiting the plasmas, which are directly related to the densities of the corresponding ions in the plasma.…”

Fast particles in a steady-state compact FNS and compact ST reactor

“…Finally, we calculate the helium ash accumulation in a bigger, but still compact ST reactor (R 0 = 1 m; B T = 5 T) [3] and compare this to the larger ITER [17] and STPP [18,19] devices. We do this by assuming that the alpha confinement time (τ α ) is some factor R larger than the energy confinement time (τ E ) and throughout a discharge the density is fixed at some fraction of the Greenwald limit.…”

Design of the stripping unit and the electromagnetic analysis unit for the E//B NPA on HL-2A/2M tokamak

“…In an LHD device, it measures the flux of fast neutrals with different energies [3], enhancing the understanding of fast ion behavior [4]. In the future device like ITER, E // B NPA will be applied to measure the D/T fuel ratio [5]. The high-energy particle fluxes of D and H are measured on JET tokamak during ICRF heating experiment with an E // B NPA [6].…”