Plasma rotation and thermonuclear neutron emission estimates in JET deuterium tritium plasmas from neutron spectroscopy

Abstract Data from the magnetic proton recoil spectrometer (MPRu) high-resolution neutron spectrometer has been used to estimate two fusion plasma quantities, the plasma rotation and the thermonuclear neutron emission. This paper presents a framework for this method and the current results for a selection of plasma discharges from the JET DTE3 campaign. Data collection during DTE3 was preceded by a hardware upgrade in the form of new digitizers, and an update to the data reduction software. The method involves simulations with the TRANSP code, the DRESS code, and a detector response function. The plasma rotation and thermonuclear neutron emission are estimated through a fit of the simulated detector response to the MPRu measurement data. This exploratory analysis studied a selection of DTE3 discharges with high neutron rates. It was found that the rotation was typically in the range <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>1.5</mml:mn> <mml:mo>×</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>5</mml:mn> </mml:msup> </mml:mrow> <mml:mrow> <mml:mtext> to </mml:mtext> </mml:mrow> <mml:mn>2.5</mml:mn> <mml:mo>×</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>5</mml:mn> </mml:msup> </mml:mrow> <mml:mrow> <mml:mtext> </mml:mtext> </mml:mrow> </mml:mrow> </mml:math> rad s −1 and that neutrons from thermonuclear reactions constitute about 10%–30% of the total neutron emission. For the studied discharges, the neutron emissivity is strongly weighted to the plasma core. Due to the MPRu line of sight passing through the plasma core twice, the plasma rotation and the thermonuclear neutron emission are estimated in the core. This method has the potential to provide complementary data points to other diagnostics.