Calculated neutron emission spectrum with knock-on effects for RF heated (³He)D plasmas

Abstract

The neutron emission from (3He)D plasmas with RF heating is calculated using a model that includes supra-thermal (knock-on) components of the deuteron population. The RF generation of fast 3He ions is described and the knock-on components were determined with the help of newly derived 3He + d scattering cross sections. Results are presented on the neutron emission spectrum and its contributions from different deuteron velocity components. It is shown that knock-on leaves an observable feature in the spectrum with a clear dependence on absorbed RF power. The importance of the nuclear interaction in the elastic cross section is demonstrated. The results represent a step forward in the use of neutron emission spectroscopy to diagnose fusion plasmas with minority supra-thermal components in their fuel ion composition.

Dual sightline measurements of MeV range deuterons with neutron and gamma-ray spectroscopy at JET

“…This corresponds to pitch angles close to 90 degrees. In previous neutron and gamma spectrometry analysis of similar plasma scenarios, pitch angles distributed as a Gaussian function with FWHM between 80 and 100 degrees were assumed in the calculations [35,36,9] to account for the pitch angle anisotropy and this is assumed also in the present paper. The fit sensitivity to specific assumptions on the pitch angle is discussed later on in section 5.…”

Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus

“…13 These instruments typically show a good energy resolution (between 5% and 7%) and a wide dynamic range sensitivity (up to 5 orders of magnitude in the case of proton recoil) that allows detecting even the very small components (at the 10 −3 -10 −5 level) induced by fast ion nuclear elastic scattering in the plasma. [14][15][16] Besides detailed spectroscopy measurements at high accuracy along a single line of sight, there is, however, a need to enable spectroscopic information in measurements along multiple collimated lines of sight (e.g., in a neutron camera system), where the use of present days, non-compact spectrometers is impeded by practical considerations. is offered by recent advances in the production of chemical vapor deposition, single crystal diamond detectors (SDDs) that, being compact, radiation resistant, and insensitive to magnetic fields, are ideal candidates for this type of application.…”

Neutron measurements from beam-target reactions at the ELISE neutral beam test facility

“…[1][2][3][4][5] Based on this experience, 2.5 MeV neutron measurements have also been proposed as diagnostics of the beam homogeneity for the SPIDER and MITICA Neutral Beam Injection (NBI) prototypes in Padua. In these devices, neutron emission will be used to measure the footprint of the deuterium beam when it hits the dump.…”