High Z neoclassical transport: Application and limitation of analytical formulae for modelling JET experimental parameters

Breton, S.; Casson, F. J.; Bourdelle, C.; Angioni, C.; Belli, E. A.; Camenen, Y.; Citrin, J.; Garbet, X.; Sarazin, Y.; Sertoli, M.; Contributors, Jet

doi:10.1063/1.5019275

Cited by 17 publications

(24 citation statements)

References 29 publications

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“…We have performed the 2D PIC simulations in a plane wave approximation with an infinite spot-size. In the 3D scenario a smaller amplitude TNSA field will appear on the rear-side of the target according to Xiao et al [36], which results in a quasimonoenergetic distribution for the CSA ions [14]. Even with this small amplitude TNSA field, the ions with different hZ=Ai will be accelerated to the different velocities.…”

Section: Discussion and Summarymentioning

confidence: 99%

Enhancement of collisionless shock ion acceleration by electrostatic ion two-stream instability in the upstream plasma

Kumar

Sakawa

Döhl

et al. 2019

Phys. Rev. Accel. Beams

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Ion acceleration in electrostatic collisionless shocks is driven by the interaction of the high-power laser with specially tailored near-relativistic critical density plasma. 2D EPOCH particle-in-cell simulations show that the ion acceleration is dependent on the target material used. In materials with low charge-tomass ratio hZ=Ai, proton beams with high flux and low energy spread are generated. In multi-ion plasmas the ions with different hZ=Ai acquire different velocities under a non-oscillating component of electrostatic field in the upstream region. This relative drift between the protons (hZ=Ai ¼ 1) and the lower hZ=Ai ions leads to the excitation of electrostatic ion two-stream instability. This in turn generates a low-velocity component in the upstream expanding protons. The velocity distribution of the upstream expanding protons is further broadened toward the higher velocity by the electrostatic ion two-stream instability between reflected protons, which results in large number of protons being accelerated by the shock.

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Section: Discussion and Summarymentioning

confidence: 99%

Enhancement of collisionless shock ion acceleration by electrostatic ion two-stream instability in the upstream plasma

Kumar

Sakawa

Döhl

et al. 2019

Phys. Rev. Accel. Beams

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“…2015; Breton et al. 2018 b ). All quantities are flux-surface averages (FSA), including the left-hand side of the equation.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…2015), the radial impurity flux can be modelled following Breton et al. (2018 b , equation (7)). If the particle flux is zero and the profiles are in equilibrium, the normalized impurity density gradient can then be calculated as, where is the tokamak major radius, the gradient length of quantity , the mass of the main ion and its temperature, the impurity charge, , and factors that depend on the collisionality, the fraction of circulating particles, and the geometrical factors related to poloidal asymmetries (Casson et al.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…where R is the tokamak major radius, L A = A/∇A the gradient length of quantity A, m I the mass of the main ion I and T I its temperature, q s the impurity charge, H, H 0 and K factors that depend on the collisionality, f c the fraction of circulating particles, P A and P B the geometrical factors related to poloidal asymmetries (Casson et al 2015;Breton et al 2018b). All quantities are flux-surface averages (FSA), including the lefthand side of the equation.…”

Section: Inclusion Of a Secondary Mid-/high-z Impuritiesmentioning

confidence: 99%

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Measuring the plasma composition in tokamaks with metallic plasma-facing components

et al. 2019

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In present and future magnetic confined fusion devices with metallic plasma-facing components (PFCs) such as JET-ILW and ITER, the calculation of the plasma composition must account for multiple impurities of a wide range of mass and charge, resolve their poloidal asymmetries and account for different central peakings for various elements. Single measurements of radiation and effective charge are not enough to characterize this complex system and a self-consistent analysis of data from multiple diagnostics is required. This contribution describes a method to calculate the plasma composition simultaneously accounting for contributions of up to two low-Z impurities, and two mid-/high-Z impurities. The analysis stems from methodologies explained in Sertoli et al. (Rev. Sci. Instrum., vol. 89 (11), 2018, 113501), expanded to include more impurities and to coherently analyse multiple diagnostics within the same framework. The example Ne-seeded JET-ILW hybrid discharge reported here shows that Be, Ne, Ni and W are necessary to simultaneously explain the observed soft X-ray emission, the W concentration measured by passive vacuum ultra-violet spectroscopy, the line-of-sight integrated measurement of the effective charge, the observed poloidal asymmetry of the soft X-ray (SXR) emission, the Ne density measured by charge-exchange-recombination spectroscopy and the line-of-sight integrals of the total radiation as measured by bolometry. This consistent picture of the elemental composition enables the calculation of the radial profiles of the effective charge, the dilution and total radiation. For the cases analysed up to now, these are often very different from the typical assumptions presently used when modelling JET-ILW discharges. This will affect, among others, the calculation of neutron rates, current density profile and heat transport. These considerations are of course valid for all present and future magnetic-controlled fusion devices which exhibit multi-material plasma-facing components, including ITER.

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“…The other parameter impacting significantly the W neoclassical transport is the rotation. The impact of poloidal asymmetries in the W neoclasscal transport is accounted for in the geometrical terms P A and P B terms in equation 2 of [35], and their range of applicability is studied in [38]. In this specific rotating JET-ILW pulse, these geometrical First principle integrated modeling of multi-channel transport including Tungsten in JET21 factors enhance the neoclassical convection up to a factor 40.…”

Section: Toroidal Rotationmentioning

confidence: 99%

First principle integrated modeling of multi-channel transport including Tungsten in JET

et al. 2018

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For the first time, over five confinement times, the self-consistent flux driven time evolution of heat, momentum transport and particle fluxes of electrons and multiple ions including Tungsten (W) is modeled within the integrated modeling platform JETTO [Romanelli M et al PFR 2014], using first principle-based codes: namely, QuaLiKiz [Bourdelle C. et al. PPCF 2016] for turbulent transport and NEO [Belli E A and Candy J PPCF 2008] for neoclassical transport. For a JET-ILW pulse, the evolution of measured temperatures, rotation and density profiles are successfully predicted and the observed W central core accumulation is obtained. The poloidal asymmetries of the W density modfying its neoclassical and turbulent transport are accounted for. Actuators of the W core accumulation are studied: removing the central particle source annihilates the central W accumulation whereas the suppression of the torque reduces significantly the W central accumulation. Finally, the presence of W slightly reduces main ion heat turbulent transport through complex nonlinear interplays involving radiation, effective charge impact on ITG and collisionality.

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High Z neoclassical transport: Application and limitation of analytical formulae for modelling JET experimental parameters

Cited by 17 publications

References 29 publications

Enhancement of collisionless shock ion acceleration by electrostatic ion two-stream instability in the upstream plasma

Enhancement of collisionless shock ion acceleration by electrostatic ion two-stream instability in the upstream plasma

Measuring the plasma composition in tokamaks with metallic plasma-facing components

First principle integrated modeling of multi-channel transport including Tungsten in JET

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