open access publication

Article, 2024

Fast-ion orbit origin of neutron emission spectroscopy measurements in the JET DT campaign

Nuclear Fusion, ISSN 0029-5515, 1741-4326, Volume 64, 2, Page 026015, 10.1088/1741-4326/ad1a57

Contributors

Järleblad, Henrik 0000-0003-1126-686X (Corresponding author) [1] Stagner, Luke 0000-0001-5516-3729 [2] Eriksson, Jacob 0000-0002-0892-3358 [3] Nocente, Massimo 0000-0003-0170-5275 [4] Kirov, Krassimir 0000-0001-8104-4782 [5] [6] Rud, Mads [1] Schmidt, Bo Simmendefeldt 0000-0001-5302-9489 [1] Maslov, Mikhail 0000-0001-8392-4644 [5] [6] King, Damian B [6] [7] Keeling, David [6] [7] Maggi, Costanza F [6] [7] Garcia, Jeronimo [8] Lerche, Ernesto Augusto [9] Mantica, Paola 0000-0001-5939-5244 [10] Dong, Yiqiu 0000-0001-8363-9448 [1] Salewski, Mirko 0000-0002-3699-679X [1] Contributors, JET

Affiliations

  1. [1] Technical University of Denmark
    2. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
  2. [2] General Atomics (United States)
    3. [NORA names: United States; America, North; OECD];
  3. [3] Uppsala University
    4. [NORA names: Sweden; Europe, EU; Nordic; OECD];
  4. [4] University of Milano-Bicocca
    5. [NORA names: Italy; Europe, EU; OECD];
  5. [5] UKAEA, Culham Centre for Fusion Energy, Abingdon, Oxfordshire OX14 3DB, United Kingdom of Great Britain and Northern Ireland
    6. [NORA names: United Kingdom; Europe, Non-EU; OECD];

Abstract

In the JET DTE2 deuterium-tritium campaign, neutron diagnostics were employed to measure 14 MeV neutrons originating from D(T,n)4He reactions. In discharge 99965, a diamond matrix detector (KM14) and a magnetic proton recoil (MPRu) detector with a vertical and an oblique line-of-sight were used, respectively. At the timepoints of interest, a significant decrease in the expected diagnostic signals can be observed as electromagnetic wave heating in the ion cyclotron range of frequencies (ICRF) is switched off. Utilizing only TRANSP simulation data, the fast-ion distribution is found to have been likely composed mostly of trapped orbits. In contrast, analysis performed using orbit weight functions revealed that the majority of neutrons in the KM14 Ed=9.3 MeV and MPRu Xcm=33 cm measurement bins are to have originated from fast deuterium ions on co-passing orbits. This work explains the perhaps surprising results and shows that the relative signal decrease as ICRF heating is switched off is largest for counter-passing orbits. Finally, for the magnetic equilibria of interest, it is shown how stagnation orbits, corresponding to ∼1 % of the fast-ion distribution, were completely unobservable by the KM14 diagnostic.

Keywords

D(t, DT campaign, JET DT campaign, MPRu, MeV, MeV neutrons, TRANSP, analysis, bins, campaign, counter-passing orbits, data, decrease, detector, deuterium, deuterium ions, deuterium–tritium campaign, diagnostic signals, diagnostics, diamond, discharge, distribution, electromagnetic wave heating, emission spectroscopy measurements, equilibrium, fast ion distribution, fast ions, frequency, function, heat, ion cyclotron range, ion cyclotron range of frequencies, ion cyclotron range of frequency heating, ions, jet, line-of-sight, magnetic equilibrium, magnetic proton recoil, matrix detector, measurement bins, measurements, n)4He reaction, neutron, neutron diagnostics, neutron emission spectroscopy measurements, oblique line of sight, orbit, orbital origin, origin, proton recoil, range of frequencies, reaction, recoil, results, signal, simulated data, spectroscopy measurements, stagnation, stagnation orbits, timepoints, trapped orbits, vertically, wave heating, weight function

Funders

  • European Commission
  • The Velux Foundations

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