Energy-selective confinement of fusion-born alpha particles during internal relaxations in a tokamak plasma

Bierwage, Andreas; Shinohara, K.; Kazakov, Ye. O.; Kiptily, V.; Lauber, P.; Nocente, M.; Štancar, Žiga; Sumida, S.; Yagi, M.; García, J.; Ide, S.

doi:10.1038/s41467-022-31589-6

Cited by 18 publications

(48 citation statements)

References 66 publications

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“…These observations appear to be in agreement with those by Bierwage et al in which high energy, co-passing, alpha particles experience moderate transport while lower energies undergo more drastic profile flattening [35]. The resonant transport at high pitch and energy presented in figure 13 demonstrates the effect captured by Bierwage et al, and how the sawtooth can redistribute certain classes of particles with weak losses.…”

Section: Discussionsupporting

confidence: 89%

“…The resonant transport at high pitch and energy presented in figure 13 demonstrates the effect captured by Bierwage et al, and how the sawtooth can redistribute certain classes of particles with weak losses. In contrast to the reduced modeling presented in this manuscript, the work in reference [35] uses a higher fidelity model and also lacks the presence of the saturated kink mode. Both models present a difference between low and high energy fusion product resonances with the sawtooth mode which warrants further detailed investigation.…”

Section: Discussionmentioning

confidence: 99%

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Numerical studies on saturated kink and sawtooth induced fast ion transport in JET ITER-like plasmas

Bonofiglo¹,

Podestà²,

Vallar³

et al. 2022

Nucl. Fusion

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This presentation examines the energetic particle transport induced by saturated kink modes and sawtooth crashes in JET deuterium plasmas. It is known that kink mode-resonant transport and phase-space redistribution from sawtooth crashes can drive strong fast ion transport with dependencies on particle pitch and energy. Measurements with JET's Faraday cup fast ion loss detector array have shown that the internal kink growth phase preceding sawtooth crashes produces substantial fast ion losses. This report will numerically investigate the dominant energetic particle transport mechanism with a detailed examination of the fast ion phase-space dependencies, resonances, orbit topology changes, induced losses, and redistribution associated with the long-lived, resonant, kink mode and non-resonant sawtooth crash. The ORBIT-kick model forms the basis of the transport studies with realistic fast ion distributions produced from TRANSP. A recently created reduced model for sawtooth induced transport is used while the saturated kink modes are modeled with ideal MHD codes. The simulations were further validated against experiment with a newly developed synthetic Faraday cup fast ion loss detector in addition to scintillator probe and neutron measurements.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Numerical studies on saturated kink and sawtooth induced fast ion transport in JET ITER-like plasmas

Bonofiglo¹,

Podestà²,

Vallar³

et al. 2022

Nucl. Fusion

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“…Additionally, significant effort was invested into validating TRANSP's synthetic diagnostics and fast ion output against experiments, e.g. the NBI and NBI+RF synergy fast ion distribution function calculations [15,77,96,97], and study of fusion products and their effects on diagnostics [18,[98][99][100]. The compilation of a database of reliable D and D-T interpretive TRANSP runs is largely owed to a JET-wide continuous investment into the improvement of diagnostics data validation and processing, modelling framework development, and unification of modellers' assumption and techniques.…”

Section: Discussionmentioning

confidence: 99%

Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Štancar,

Kirov,

Auriemma

et al. 2023

Nucl. Fusion

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In the paper we present an overview of interpretive modelling of a database of JET-ILW 2021 D-T discharges using the TRANSP code. The main aim is to assess our capability of computationally reproducing the fusion performance of various D-T plasma scenarios using different external heating and D-T mixtures, and to understand the performance driving mechanisms. We find that interpretive simulations confirm a general power-law relationship between increasing external heating power and fusion output, which is supported by absolutely calibrated neutron yield measurements. A comparison of measured and computed D-T neutron rates shows that the calculations’ discrepancy depends on the absolute neutron yield. The calculations are found to agree well with measurements for higher performing discharges with external heating power above ∼20 M W , while low-neutron shots display an average discrepancy of around +40% compared to measured neutron yields. A similar trend is found for the ratio between thermal and beam-target fusion, where larger discrepancies are seen in shots with dominant beam-driven performance. We compare the observations to studies of JET-ILW D discharges, to find that on average the fusion performance is well modelled over a range of heating power, although an increased unsystematic deviation for lower-performing shots is observed. The ratio between thermal and beam-induced D-T fusion is found to be increasing weakly with growing external heating power, with a maximum value of ≳ 1 achieved in a baseline scenario experiment. An evaluation of the fusion power computational uncertainty shows a strong dependence on the plasma scenario type and fusion drive characteristics, varying between ±25% and 35%. D-T fusion alpha simulations show that the ratio between volume-integrated electron and ion heating from alphas is ≲ 10 for the majority of analysed discharges. Alphas are computed to contribute between ∼15% and 40% to the total electron heating in the core of highest performing D-T discharges. An alternative workflow to TRANSP was employed to model JET D-T plasmas with the highest fusion yield and dominant non-thermal fusion component because of the use of fundamental radio-frequency heating of a large minority in the scenario, which is calculated to have provided ∼10% to the total fusion power.

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“…Assuming triangular sawtooth traces as funtion of time, the pressure profile recovers linearly in time along the ramp. On the other hand, in the limit where the fast ion precession frequncy is large as compared to the sawtooth crash time, high energy alpha particles are not affected Kadomtsev radial mixing and remain confined in the core, as discussed in [12].…”

Section: Fast-ion Resonancementioning

confidence: 99%

Axisymmetric modes, fast ions and X-point effects in tokamak plasmas

Barberis

Porcelli

Fitzpatrick

et al. 2022

J. Phys.: Conf. Ser.

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Energy-selective confinement of fusion-born alpha particles during internal relaxations in a tokamak plasma

Cited by 18 publications

References 66 publications

Numerical studies on saturated kink and sawtooth induced fast ion transport in JET ITER-like plasmas

Numerical studies on saturated kink and sawtooth induced fast ion transport in JET ITER-like plasmas

Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Axisymmetric modes, fast ions and X-point effects in tokamak plasmas

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