Neutron spectroscopy measurements of tritium beam transport at JET

Abstract

A detailed description of the 14 MeV neutron emission in plasmas heated by neutral beam injection has been carried out by coupling Monte Carlo calculations of the neutron emission spectrum with TRANSP modelling of the beam ion energy distributions. The model is used to study tritium beam injection experiments of the JET trace tritium campaign for internal transport barrier (ITB) and H-mode discharges. For ITB discharges, the measured neutron emission spectrum is well described by modelling using as input the beam ion distribution calculated with TRANSP. For H mode discharges the neutron spectrum can be reproduced only if high energy tritons are lost from the plasma, suggesting the possible role of low frequency tearing modes on the beam ions. The presented results are of relevance for tritium beam transport studies in trace tritium experiments and, more generally, for deuterium and tritium transport studies in high power experiments using neutron emission spectroscopy.

Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

“…This information could be used for fast ion studies, as demonstrated so far in present tokamaks with dedicated high resolution spectrometers such as MPRu and TOFOR. [43][44][45][46] Adding spectroscopy information to a neutron camera system by means of compact detectors would allow for spatially resolved measurements of the fast ion energy distribution in a high performance device.…”

Experimental investigation of beam-target neutron emission at the ELISE neutral beam test facility

“…In fusion plasmas, 2.5 MeV neutron measurements are traditionally used to provide information of the fuel ion energy distribution in tokamaks [1,2,3]. More recently, as the focus of fusion 5 research progressively shifts from physics to technological applications, 2.5 MeV neutron detectors using Gas Electron Multipliers [4] have been also proposed as diagnostics of the beam homogeneity for the SPIDER and MITICA Neutral Beam In- 10 jection Prototypes (NBI) in Padua.…”

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

“…They can be used to extract essential parameters for machine control, such as the fuel ion temperature, 1 the thermal/non-thermal components of the neutron emission, 2,3 and the fuel ion ratio. 4 More recently, they have contributed to fundamental studies on the physics of suprathermal ions in thermonuclear plasmas, mostly by detailed measurements of the distribution function of the energetic ions [5][6][7] and their effects on the plasma stability.…”