Reconstruction of the fast-ion deuterium distribution in a tritium-rich plasma in the JET DTE2 campaign
H. Järleblad, Bernard Reman, Yiqiu Dong, M. Nocente, J. Eriksson, A. Valentini, M. Rud, A. Dal Molin, J. García, Y. Kazakov, D. Keeling, D. King, E. Lerche, R. Lorenzini, C. F. Maggi, M. Maslov, D. Moseev, D. Rigamonti, Bo Simmendefeldt Schmidt, Ž. Štancar, M. Tardocchi, M. Salewski, JET Contributors, the EUROfusion Tokamak Exploitation Team
Abstract
Abstract An important step on the way to future fusion power plants was the 2021 deuterium–tritium experimental campaign (DTE2) at the Joint European Torus (JET), in which crucial DT physics was investigated. In this study, we have reconstructed the fast-ion deuterium distribution function in JET discharge 99971 which broke the former fusion energy record. It is the first time that the fast-ion distribution has been reconstructed from experimental data in a DT discharge. The reconstruction shows that the fast-ion deuterium distribution is anisotropic, with a bias towards co-going ions ( p > 0). The fast-ion deuterium distribution likely peaks in energy ( E ) at around <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>E</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>60</mml:mn> </mml:mrow> </mml:math> –70 keV and has a marginal high-energy tail ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>E</mml:mi> <mml:mo>≳</mml:mo> <mml:mn>180</mml:mn> </mml:mrow> </mml:math> keV). Furthermore, an orbit analysis shows that the fast-ion distribution is composed of mostly co-passing orbits ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> ), trapped orbits ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>21</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> ) and counter-passing orbits ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>27</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> ), as well as a small population of potato orbits ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>1.7</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> ) and counter-stagnation orbits ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>0.3</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:mrow> </mml:math> ). The orbit-type constituents of the neutron measurements are distributed in similar fractions.