Recent H majority inverted radio frequency heating scheme experiments in JET-ILW

Eester, D. Van; Lerche, E.; Kazakov, Yevgen; Jacquet, Philippe; Baranov, Y.; Bobkov, V.; Crombé, Kristel; Czarnecka, A.; Dümont, R.; Dumortier, P.; Eriksson, J.; Giacomelli, L.; Giroud, C.; Goniche, M.; Hellesen, C.; Kiptily, V.; Krawczyk, N.; Koskela, T.; Nave, F.; Nocente, M.; Ongena, J.; Santala, M.; Salewski, M.; Schneider, M.; Weisen, H.

doi:10.1051/epjconf/201715703061

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…[39]. The results verify the JET-ILW experimental findings that near-axial resonances produce the highest power densities when deposition is within +/-10cm of the magnetic axis [40][41][42][43]. The He-3 minority yields a larger ion-heating fraction than H-minority as well as a slightly narrower collisional power deposition due to increased collisionality and reduced orbit widths.…”

Section: Fidelity Of Icrh Modelling and Impact Of Icrh Minority Anisotropysupporting

confidence: 74%

“…Next, we compare the effects of electron vs ion heating schemes with the same total power density for controlling W accumulation (figure 8(b), an optimisation which is not a priori obvious, or known from JET experiments [40,42]. The simulations make a clear prediction, as yet untested for the JET hybrid scenario: ion heating schemes should delay the arrival of W on axis.…”

Section: Optimisation Of Heating Against W Accumulationmentioning

confidence: 99%

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Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET

Casson¹,

Patten²,

Bourdelle³

et al. 2020

Nucl. Fusion

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The evolution of the JET high performance hybrid scenario, including central accumulation of the tungsten (W) impurity, is reproduced with predictive multi-channel integrated modelling over multiple confinement times using first-principle based core transport models. 8 transport channels (𝑇 𝑖 , 𝑇 𝑒 , 𝑗, 𝑛 𝐷 , 𝑛 𝐵𝑒 , 𝑛 𝑁𝑖 , 𝑛 𝑊 , 𝜔) are modelled predictively, with self-consistent sources, radiation and magnetic equilibrium, yielding a system with multiple non-linearities: This system can reproduce the observed radiative temperature collapse after several confinement times. W is transported inward by neoclassical convection driven by the main ion density gradients and enhanced by poloidal asymmetries due to centrifugal acceleration. The slow evolution of the bulk density profile sets the timescale for W accumulation. Modelling this phenomenon requires a turbulent transport model capable of accurately predicting particle and momentum transport (QuaLiKiz) and a neoclassical transport model including the effects of poloidal asymmetries (NEO) coupled to an integrated plasma simulator (JINTRAC). The modelling capability is applied to optimise the available actuators to prevent W accumulation, and to extrapolate in power and pulse length. Central NBI heating is preferred for high performance, but gives central deposition of particles and torque which increase the risk of W accumulation by increasing density peaking and poloidal asymmetry. The primary mechanism for ICRH to control W in JET is via its impact through turbulence in reducing main ion density peaking (which drives inward neoclassical convection), increased temperature screening and turbulent W diffusion. The anisotropy from ICRH also reduces poloidal asymmetry, but this effect is negligible in high rotation JET discharges. High power ICRH near the axis can sensitively mitigate against W accumulation, and dominant ion heating (e.g. He-3 minority) is predicted to provide more resilience to W accumulation than dominant electron heating (e.g. H minority) in the JET hybrid scenario. Extrapolation to DT plasmas finds 17.5MW of fusion power and improved confinement compared to DD, due to reduced ion-electron energy exchange, and increased Ti/Te stabilisation of ITG instabilities. The turbulence reduction in DT increases density peaking and accelerates the arrival of W on axis; this may be mitigated by reducing the penetration of the beam particle source with an increased pedestal density.

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Section: Fidelity Of Icrh Modelling and Impact Of Icrh Minority Anisotropysupporting

confidence: 74%

Section: Optimisation Of Heating Against W Accumulationmentioning

confidence: 99%

Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET

Casson¹,

Patten²,

Bourdelle³

et al. 2020

Nucl. Fusion

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“…In support of deuterium-tritium (D-T) experiments scheduled for 2019-2020, JET conducted the experimental campaign C37 'Hydrogen' with hydrogen-deuterium (H-D) plasmas in 2016 [1]. The campaign was aimed at solving the following tasks: (i) controlling the isotope ratio using various scenarios of fuelling with gas puffing and pellets [2], (ii) investigation of the influence of the isotope ratio on the plasma confinement, L-H transition [3] and density limit in the H-mode [4], (iii) testing various scenarios of plasma heating using neutral beam injection (NBI) and/or ion-cyclotron resonance (ICRH) [5,6], etc [1]. The hydrogen concentration was varied from 1% to 99% during the campaign.…”

Section: Introductionmentioning

confidence: 99%

Determination of isotope ratio in the divertor of JET-ILW by high-resolution Hα spectroscopy: H–D experiment and implications for D–T experiment

et al. 2019

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The data of the Hα high-resolution spectroscopy, collected on the multiple lines of sight, which cover the entire divertor space in poloidal cross-section, during the recent hydrogen-deuterium experiments in JET-ILW (ITER-like wall), are processed. A strong spatial inhomogeneity of the hydrogen concentration, H/(H + D), in divertor is found in many pulses. Namely, the H/(H + D) ratio may be lower in the inner divertor than that in the outer divertor by the values of 0.15–0.35, depending on the conditions of gas puffing and plasma heating. This effect suggests the necessity of spatially-resolved measurements of isotope ratio in the divertor in the upcoming deuterium–tritium experiments. Also, separation of the overlapped Tα and Dα spectral lines is shown to be a challenging task especially when the local Doppler-broadened (Gaussian) line shapes are noticeably distorted by the net inward flux of fast non-Maxwellian neutral atoms. We use the respective, formerly developed model of an asymmetric spectral line shape, while analysing the data of the first deuterium–tritium experiment in JET-C (carbon wall), and test the model via comparing the isotope ratio results with another diagnostic’s measurements. This model is shown to increase the accuracy of tritium concentration measurements in the divertor.

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Summary of the 27th IAEA Fusion Energy Conference in the categories of EX/W, EX/D, and ICC

Ida

2019

Nucl. Fusion

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The results in the categories of EX/W (wave-plasma interactions, current drive, heating, energetic particles), EX/D (plasma-material interactions, divertors, limiters, scrape-off layer (SOL)), and ICC (innovative confinement concepts) in magnetic confinement experiments are summarized. In total, 121 papers have been contributed to these categories. Interesting results on the coupling between energetic particles, MHD, wave-particle interaction, turbulence, SOL physics, and divertor are presented at this conference. For example, control of energetic particle driven MHD by electron cyclotron heating and resonance magnetic perturbation, mitigation of disruption by energetic particle driven MHD, control of decay length by SOL turbulence, and wave scattering by SOL density fluctuations were discussed in this conference. Deeper understanding of these couplings will be essential for the sustainment of high performance steady-state plasma in ITER.

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Recent H majority inverted radio frequency heating scheme experiments in JET-ILW

Cited by 4 publications

References 16 publications

Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET

Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET

Determination of isotope ratio in the divertor of JET-ILW by high-resolution Hα spectroscopy: H–D experiment and implications for D–T experiment

Summary of the 27th IAEA Fusion Energy Conference in the categories of EX/W, EX/D, and ICC

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