Quiescent Double Barrier Regime in the DIII-D Tokamak

Greenfield, C. M.; Burrell, K.H.; DeBoo, J. C.; Doyle, E. J.; Stallard, B. W.; Synakowski, E. J.; Fenzi, C.; Gohil, P.; Groebner, R. J.; Lao, L. L.; Makowski, M. A.; McKee, G. R.; Moyer, R. A.; Rettig, C. L.; Rhodes, T. L.; Pinsker, R. I.; Staebler, G. M.; West, W.P.; Team, Diii-D

doi:10.1103/physrevlett.86.4544

Cited by 140 publications

(132 citation statements)

References 37 publications

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“…(27) energy input to the ions, including the auxiliary heating and the electron-ion exchange term. Equation (27) is then used to obtain an approximate value for a thermal diffusivity from the (presumed known) sources. The simplest thing to do is to define an effective thermal diffusivity by,…”

Section: Q V Dv S P I a Amentioning

confidence: 99%

“…This is done by subtracting αΓT from both sides of Eq. (27), where α is a number, usually either 5/2 or 3/2. 11,21-22 A value of 5/2 is strictly only appropriate for collisional transport if r u ⋅ ∇p is small or when r u ⋅ ∇p can be approximated by u p r * ∇ .…”

Section: Q V Dv S P I a Amentioning

confidence: 99%

“…Inspection of Eq. (27) shows that it is not appropriate for turbulent transport. If χ i,a , and Γ a are small, then using 3/2 would result in a "conductive" term which is approximately 3 2n Tṽ E r , however this is in fact a "convective" term, leading perhaps to the conclusion that Eq.…”

Section: Q V Dv S P I a Amentioning

confidence: 99%

“…As an example we consider the results of a TRANSP 26 analysis of a DIII-D long pulse high performance quiescent double barrier (QDB) 27 discharge. Figure 1 shows the time history of the relevant parameters of this discharge.…”

Section: Q V Dv S P I a Amentioning

confidence: 99%

“…15 This is exemplified by Eq. (27), the expression for the energy flux. There is only one term in the expression which is clearly a diffusive or "conductive" term and there is no way to unambiguously separate that term from the others since, without an exact calculation of all of the terms, the relative sizes of the terms is unknown.…”

Section: Conclusion and Summarymentioning

confidence: 99%

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The effect of turbulent stresses on the experimental determination of a thermal diffusivity due to turbulent transport

Baker¹

2003

Plasma Phys. Control. Fusion

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In plasmas where the transport processes are dominated by turbulence, it is not always straightforward to identify the magnitude of the experimental transport diffusion coefficients. This is primarily due to the fact that with turbulent transport, the separation of the convective and conductive terms depends upon the type of turbulence and/or the model which is used to describe it. For the energy transport it is not just a matter of deciding whether the convection term is 5/2 or 3/2 times the product of the particle flux and the temperature. It is also important to identify turbulence generated convection terms such as heat pinches which can obscure the correct evaluation of the thermal diffusivity. Here we show that inclusion of the turbulence induced stresses into the transport model identifies a heat pinch term and changes the expression for the thermal diffusivity. Comparison with experimental results shows that the new calculated ion thermal diffusivity is no longer less than the neoclassical value even for plasmas with very good ion thermal confinement.

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Section: Q V Dv S P I a Amentioning

confidence: 99%

Section: Q V Dv S P I a Amentioning

confidence: 99%

Section: Q V Dv S P I a Amentioning

confidence: 99%

Section: Q V Dv S P I a Amentioning

confidence: 99%

Section: Conclusion and Summarymentioning

confidence: 99%

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The effect of turbulent stresses on the experimental determination of a thermal diffusivity due to turbulent transport

Baker¹

2003

Plasma Phys. Control. Fusion

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Insights into type‐I edge localized modes and edge localized mode control from JOREK non‐linear magneto‐hydrodynamic simulations

Hoelzl

Huijsmans

Orain

et al. 2018

Contributions to Plasma Physics

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Edge localized modes (ELMs) are repetitive instabilities driven by the large pressure gradients and current densities in the edge of H‐mode plasmas. Type‐I ELMs lead to a fast collapse of the H‐mode pedestal within several hundred microseconds to a few milliseconds. Localized transient heat fluxes to divertor targets are expected to exceed tolerable limits for ITER, requiring advanced insights into ELM physics and applicable mitigation methods. This paper describes how non‐linear magneto‐hydrodynamic (MHD) simulations can contribute to this effort. The JOREK code is introduced, which allows the study of large‐scale plasma instabilities in tokamak X‐point plasmas covering the main plasma, the scrape‐off layer, and the divertor region with its finite element grid. We review key physics relevant for type‐I ELMs and show to what extent JOREK simulations agree with experiments and help reveal the underlying mechanisms. Simulations and experimental findings are compared in many respects for type‐I ELMs in ASDEX Upgrade. The role of plasma flows and non‐linear mode coupling for the spatial and temporal structure of ELMs is emphasized, and the loss mechanisms are discussed. An overview of recent ELM‐related research using JOREK is given, including ELM crashes, ELM‐free regimes, ELM pacing by pellets and magnetic kicks, and mitigation or suppression by resonant magnetic perturbation coils (RMPs). Simulations of ELMs and ELM control methods agree in many respects with experimental observations from various tokamak experiments. On this basis, predictive simulations become more and more feasible. A brief outlook is given, showing the main priorities for further research in the field of ELM physics and further developments necessary.

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Edge localized modes suppression via edge E × B velocity shear induced by RF sheath of ion cyclotron resonance heating in EAST

Zhang

Zhou

Zou

et al. 2022

Sci. China Phys. Mech. Astron.

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Quiescent Double Barrier Regime in the DIII-D Tokamak

Cited by 140 publications

References 37 publications

The effect of turbulent stresses on the experimental determination of a thermal diffusivity due to turbulent transport

The effect of turbulent stresses on the experimental determination of a thermal diffusivity due to turbulent transport

Insights into type‐I edge localized modes and edge localized mode control from JOREK non‐linear magneto‐hydrodynamic simulations

Edge localized modes suppression via edge E × B velocity shear induced by RF sheath of ion cyclotron resonance heating in EAST

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