Role of NBI fuelling in contributing to density peaking between the ICRH and NBI identity plasmas on JET

Tala, T.; Eriksson, F.; Mantica, P.; Mariani, A.; Salmi, A.; Solano, E.R.; Carvalho, I.; Chomiczewska, A.; Delabie, E.; Ferreira, J.; Fransson, E.; Horváth, L.; Jacquet, Philippe; King, D.; Kirjasuo, A.; Leerink, S.; Lerche, E.; Maggi, C. F.; Marin, Michèle; Maslov, M.; Menmuir, S.; Morales, Rennan Bianchetti; Naulin, V.; Nave, M. F. F.; Nordman, Hans; Thun, C. Perez von; Schneider, P. A.; Sertoli, M.; Tanaka, K.; Contributors, Jet

doi:10.1088/1741-4326/ac5667

“…The normalised n e gradient length R/L n averaged over ρ TOR = 0.4-0.8 is R/L n = 0.93 and R/L n = 0.45 for the NBI and ICRH case, respectively. The increase in the density peaking by a factor of 2 can be explained solely by NBI fuelling, since, according to GENE and TGLF simulations, the background transport is the same between the ICRH and NBI discharges [58]. This result is consistent with that from a dimensionless collisionality scan in JET H-mode plasma [59], showing the NBI contributing to ∼50% of the fuelling.…”

Section: Core and Pedestal Transport And Confinementsupporting

confidence: 80%

Overview of JET results for optimising ITER operation

Mailloux

¹

,

Abid

²

,

Abraham

³

et al. 2022

Self Cite

View full text Add to dashboard Cite

The JET 2019-2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major Neutral Beam Injection (NBI) upgrade providing record power in 2019-2020, and tested the technical & procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle physics in the coming D-T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed Shattered Pellet Injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design & operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D-T benefited from the highest D-D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER.

show abstract

“…the R/L n radial profiles corresponding to simulations that locally give as output Γ profiles that are smaller and larger, respectively, than the experimental particle source Γ exp. (an example of local flux-tube GK analysis of density peaking, comparing cases from the JET tokamak with or without NBI can be found in [25]). The ZPFD approach, on the contrary, can not be so trivially generalized to a case with finite Γ exp.…”

Section: Global Zpfd Simulationsmentioning

confidence: 99%

Global ‘zero particle flux-driven’ gyrokinetic analysis of the density profile for a TCV plasma

Mariani¹,

Brunner²,

Merlo

³

et al. 2023

Plasma Phys. Control. Fusion

Self Cite

1

0

View full text Add to dashboard Cite

TCV is a small-sized tokamak, where finite size effects (often called ‘rho-star’ or ‘global’ effects) could significantly impact the heat and particle fluxes, leading to discrepancies between gyrokinetic flux-tube results and global ones [McMillan et al., 2010 Phys. Rev. Lett.]. The impact of global effects on the radial profile of the plasma density has been investigated in a previous study for a particular TCV discharge with negligible particle source, satisfying the ‘zero particle flux’ condition. A radially local flux-tube analysis, reconstructing the dependence of the peaking of the density profile on the main physical parameters, invoking the zero particle flux constraint, was pursued close to mid-radius in [Mariani et al., 2018 Phys. Plasmas]. This analysis was followed by a global one [Mariani et al., 2019 Plasma Phys. Control. Fusion], where local quasi-linear and nonlinear results were compared with global simulations, showing small global effects on the density peaking. However, these gradient-driven global runs considered Krook-type heat and particle sources to keep temperature and density profiles fixed on average, which differ from the experimental radially localized sources. To remove this possible bias on the results, a different evaluation of the density peaking for the same case is performed here, based on global nonlinear hybrid simulations where the temperature profiles are [still] kept fixed with the Krook-type sources, however the density profile relaxes in a flux-driven way (with zero particle source). The new hybrid simulations show a good agreement with the old gradient-driven runs. A global quasi-linear model is also developed and applied using the output from linear global runs, to estimate ratios of fluxes, showing a good agreement with the results of global nonlinear gradient-driven simulations. The effect of collisions on the flux-tube results is also investigated, in order to evaluate their impact on the radial variation of the density peaking.

show abstract

“…Gas puff modulation technique will be exploited here as the extra tool to quantify the core isotope scaling in the electron particle transport channel between the Deuterium and Tritium plasmas. There is a lot of previous experience at JET in using the gas puff modulation technique to analyse electron particle transport and obtain electron particle transport coefficients [22,23]. Recently, the methodology has been further refined and optimised also to be appropriately used in this isotope mass scaling experiment [24].…”

Section: Introductionmentioning

confidence: 99%

Isotope mass scaling and transport comparison between JET Deuterium and Tritium L-mode plasmas

Tala,

Järvinen,

Maggi

et al. 2023

Self Cite

View full text Add to dashboard Cite

The dimensionless isotope mass scaling experiment between pure Deuterium and pure Tritium plasmas with matched ρ ∗ , ν ∗ , β n , q and T e / T i has been achieved in JET L-mode with dominant electron heating (NBI+ohmic) conditions. 28% higher scaled energy confinement time B t τ E , t h / A is found in favour of the Tritium plasma. This can be cast in the form of the dimensionless energy confinement scaling law as Ω i τ E , t h ∼ A 0.48 ± 0.16 . This significant isotope mass scaling is consequently seen in the scaled one-fluid heat diffusion coefficient A χ e f f / B t which is around 50% lower in the Tritium plasma throughout the whole plasma radius. The isotope mass dependence in the particle transport channel is negligible, supported also by the perturbative particle transport analysis with gas puff modulation. The comparison of the edge particle fuelling or ionisation profiles from the EDGE2D-EIRENE simulations show that the absolute density differences that are necessary for the dimensionless match in the confined plasma dominate over any isotope mass dependencies of particle fuelling and ionization profiles at the plasma edge. Local GENE simulation results indicate a mild anti-gyroBohm effect at ρ t o r = 0.6 and thereby a small isotope mass dependence in favour of Tritium on heat transport and a negligible effect on particle transport. A significant fraction of the isotope scaling and reduced heat transport observed in the Tritium plasma is not captured in the GENE and ASTRA-TGLF-SAT2 simulations by simply changing the isotope mass for the same input profiles.

show abstract

Role of NBI fuelling in contributing to density peaking between the ICRH and NBI identity plasmas on JET

Cited by 4 publications

References 56 publications

Overview of JET results for optimising ITER operation

Overview of JET results for optimising ITER operation

Global ‘zero particle flux-driven’ gyrokinetic analysis of the density profile for a TCV plasma

Isotope mass scaling and transport comparison between JET Deuterium and Tritium L-mode plasmas

Contact Info

Product

Resources

About