Compact NE213 neutron spectrometer with high energy resolution for fusion applications

TLDR

Neutron spectrometry is a tool for obtaining important information on the fuel ion composition, velocity distribution and temperature of fusion plasmas. A compact NE213 liquid scintillator, fully characterized at PTB, was installed and operated at JET during two campaigns, and pulse‑height data were analyzed with a newly developed maximum‑entropy unfolding method. The spectrometer achieved ΔE/E < 4 % at 2.5 MeV and < 2 % at 14 MeV, and measurements under various plasma scenarios, including trace tritium experiments, demonstrate that the inexpensive, compact NE213 detector is suitable as a broadband neutron spectrometer for large fusion devices such as JET and ITER.

Abstract

Neutron spectrometry is a tool for obtaining important information on the fuel ion composition, velocity distribution and temperature of fusion plasmas. A compact NE213 liquid scintillator, fully characterized at Physikalisch-Technische Bundesanstalt, was installed and operated at the Joint European Torus (JET) during two experimental campaigns (C8-2002 and trace tritium experiment-TTE 2003). The results show that this system can operate in a real fusion experiment as a neutron (1.5 MeV&amp;lt;En&amp;lt;20 MeV) spectrometer with good energy resolution (ΔE/E&amp;lt;4% at En=2.5 MeV and ΔE/E&amp;lt;2% at En=14 MeV). First measurements performed under different plasma scenarios, including trace tritium experiments, are presented. The analysis of the pulse height data was carried out using a newly developed method based on maximum entropy unfolding. The results indicate that this efficient, inexpensive, and compact scintillator is suitable for use as a broadband spectrometer in large fusion devices (JET and the International Thermonuclear Experimental Reactor).