Control of the hydrogen:deuterium isotope mixture using pellets in JET

Valovič, M.; Baranov, Y.; Boboc, A.; Buchanan, J.; Citrin, J.; Delabie, E.; Frassinetti, L.; Fontdecaba, J. M.; Garzotti, L.; Giroud, C.; McKean, R.; Lerche, E.; Kiptily, V.; Köchl, F.; Marin, Michèle; Maslov, M.; Menmuir, S.; Tvalashvili, G.; Weisen, H.

doi:10.1088/1741-4326/ab3812

Cited by 9 publications

(9 citation statements)

References 26 publications

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“…Although there is presently no experimental determination of the required, minimal equilibration time, there are a number of published studies, from present generation tokamaks, from which to get a sense of time scale for this equilibration. These include (a) the JET DTE1 data of [4] in which great agreement is shown between sub-divertor and main plasma measurements (including neutrons) over a very large range of isotopic concentrations, (b) a long-pulse, particle balance study on Tore Supra in which it was specifically shown that the Penning-OGA measurement, in this case in the pumping duct of a toroidal pumped-limiter, was in full agreement with neutral particle analyzer (NPA) data from the core, thus permitting the former to continue taking data over much longer time scales than was possible for the latter diagnostic [19] (see figure 8), and (c) a recent study on JET-ILW, in which the sub-divertor isotopic concentrations match quite well the concentrations measured by the core CXS diagnostic [20]. This should however be checked (via modeling) for ITER, especially since it has already been established that isotopic measurement by divertor spectroscopy will not be feasible at low concentrations, while CXS and NPA may be quite limited in resolving small isotopic concentrations.…”

Section: Relation Between Sub-divertor and Main Plasma Isotopic Contentsupporting

confidence: 70%

Sub-divertor fuel isotopic content detection limit for JET and its impact on ICRF core heating and DTE2 operation

et al. 2019

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The ability to detect and control fuel isotopic content down to a 1% concentration level is greatly important for the upcoming JET DTE2 campaign, as well as its associated TT and DD phases. A reduction of H minority concentration even from 2% down to 1% is shown here to have significant impact on the effectiveness of ion cyclotron range of frequencies core heating, while the ability to maintain T or D concentration at or below 1% is critical to limiting fusion neutron generation in the DD and TT phases, correspondingly. The sub-divertor measurement of (global) isotopic concentration, based on Penning-activated optical spectroscopy, can deliver minimally this 1% detection for DTE2 as long as light collection from the Penning emission can be optimized and gradual window transmission deterioration can be minimized. This is simulated International Atomic Energy Agency

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Section: Relation Between Sub-divertor and Main Plasma Isotopic Contentsupporting

confidence: 70%

Sub-divertor fuel isotopic content detection limit for JET and its impact on ICRF core heating and DTE2 operation

et al. 2019

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“…This effect is much weaker than with other methods to control the ELM frequency, e.g. pellets [29] ( [30] for D-T) or vertical position kicks [31]. So far, the physics of this is not understood, especially because there is no very significant change in the pedestal top parameters.…”

Section: Elm Bunchingmentioning

confidence: 95%

The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium

Hobirk,

Challis,

Kappatou

et al. 2023

Nucl. Fusion

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The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with the ITER-like Be/W wall. The development started in pure Deuterium with refinement of the plasma current, and toroidal magnetic field choices and succeeded in solving the heat load challenges arising from 37 MW of injected power in the ITER like wall environment, keeping the radiation in the edge and core controlled, avoiding MHD instabilities and reaching high neutron rates. The Deuterium hybrid plasmas have been re-run in Tritium and methods have been found to keep the radiation controlled but not at high fusion performance probably due to time constraints. For the first time this scenario has been run in Deuterium-Tritium (50:50). These plasmas were re-optimised to have a radiation-stable H-mode entry phase, good impurity control through edge Ti gradient screening and optimised performance with fusion power exceeding 10 MW for longer than three alpha particle slow down times, 8.3 MW averaged over 5 s and fusion energy of 45.8 MJ.

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“…Core isotope ratio control has also been demonstrated by shallow (low penetration) deuterium pellets injected into a plasma simultaneously fuelled by hydrogen gas and hydrogen NBH (Valovic et al . 2019). A core H/D ratio n H / n D ≈ 1.2, close to the target of n H / n D = 1, was obtained despite the different fuelling methods for the two species, as inferred from core hydrogen isotope CXS and from the neutron rates.…”

Section: Isotope Dependence In Jet-ilw Type I Elmy H-modesmentioning

confidence: 99%

Isotope dependence of energy, momentum and particle confinement in tokamaks

Weisen

Maggi²,

Oberparleiter³

et al. 2020

J. Plasma Phys.

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The isotope dependence of plasma transport will have a significant impact on the performance of future D-T experiments in JET and ITER and eventually on the fusion gain and economics of future reactors. In preparation for future D-T operation on JET, dedicated experiments and comprehensive transport analyses were performed in H, D and H-D mixed plasmas. The analysis of the data has demonstrated an unexpectedly strong and favourable dependence of the global confinement of energy, momentum and particles in ELMy H-mode plasmas on the atomic mass of the main ion species, the energy confinement time scaling as ${\tau _E}\sim {A^{0.5}}$ (Maggi et al., Plasma Phys. Control. Fusion, vol. 60, 2018, 014045; JET Team, Nucl. Fusion, vol. 39, 1999, pp. 1227–1244), i.e. opposite to the expectations based only on local gyro-Bohm (GB) scaling, ${\tau _E}\sim {A^{ - 0.5}}$ , and stronger than in the commonly used H-mode scaling for the energy confinement (Saibene et al., Nucl. Fusion, vol. 39, 1999, 1133; ITER Physics Basis, Nucl. Fusion, vol. 39, 1999, 2175). The scaling of momentum transport and particle confinement with isotope mass is very similar to that of energy transport. Nonlinear local GENE gyrokinetic analysis shows that the observed anti-GB heat flux is accounted for if collisions, E × B shear and plasma dilution with low-Z impurities (9Be) are included in the analysis (E and B are, respectively the electric and magnetic fields). For L-mode plasmas a weaker positive isotope scaling ${\tau _E}\sim {A^{0.14}}$ has been found in JET (Maggi et al., Plasma Phys. Control. Fusion, vol. 60, 2018, 014045), similar to ITER97-L scaling (Kaye et al., Nucl. Fusion, vol. 37, 1997, 1303). Flux-driven quasi-linear gyrofluid calculations using JETTO-TGLF in L-mode show that local GB scaling is not followed when stiff transport (as is generally the case for ion temperature gradient modes) is combined with an imposed boundary condition taken from the experiment, in this case predicting no isotope dependence. A dimensionless identity plasma pair in hydrogen and deuterium L-mode plasmas has demonstrated scale invariance, confirming that core transport physics is governed, as expected, by the 4 dimensionless parameters ρ*, ν*, β, q (normalised ion Larmor radius, collisionality, plasma pressure and safety factor) consistently with global quasi-linear gyrokinetic TGLF calculations (Maggi et al., Nucl. Fusion, vol. 59, 2019, 076028). We compare findings in JET with those in different devices and discuss the possible reasons for the different isotope scalings reported from different devices. The diversity of observations suggests that the differences may result not only from differences affecting the core, e.g. heating schemes, but are to a large part due to differences in device-specific edge and wall conditions, pointing to the importance of better understanding and controlling pedestal and edge processes.

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Control of the hydrogen:deuterium isotope mixture using pellets in JET

Cited by 9 publications

References 26 publications

Sub-divertor fuel isotopic content detection limit for JET and its impact on ICRF core heating and DTE2 operation

Sub-divertor fuel isotopic content detection limit for JET and its impact on ICRF core heating and DTE2 operation

The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium

Isotope dependence of energy, momentum and particle confinement in tokamaks

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