Non-local approach to kinetic effects on parallel transport in fluid models of the scrape-off layer

Omotani, John; Dudson, B.

doi:10.1088/0741-3335/55/5/055009

Cited by 38 publications

(46 citation statements)

References 25 publications

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“…Closures of the fluid equations that might be also valid in low-collisionality regimes have been considered deriving those from kinetic models (Omotani and Dudson 2013). The fluid simulations are typically considered in the low-recycling regime, neglecting the P. Ricci interaction with the neutrals.…”

Section: Fluid Description Of the Sol Dynamicsmentioning

confidence: 99%

Simulation of the scrape-off layer region of tokamak devices

Ricci

2015

J. Plasma Phys.

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Understanding the key processes occurring in the tokamak scrape-off layer (SOL) is becoming of the outmost importance while we enter the ITER era and we move towards the conception of future fusion reactors. By controlling the heat exhaust, by playing an important role in determining the overall plasma confinement, and by regulating the impurity level in tokamak core, the dynamics of the fusion fuel in the SOL is, in fact, related to some of the most crucial issues that the fusion program is facing today. Because of the limited diagnostic access and in view of predicting the SOL dynamics in future devices, simulations are becoming crucial to address the physics of this region. The present paper, which summarizes the lecture on SOL simulations that was given during the 7th ITER international school (August 25-29, 2014, Aix-en-Provence, France), provides a brief overview of the simulation approaches to the SOL dynamics. First, disentangling the complexity of the system, the key physics processes occurring in the SOL are described. Then, the different simulation approaches to the SOL dynamics are presented, from first-principles kinetic and fluid models, to the phenomenological analysis.

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Section: Fluid Description Of the Sol Dynamicsmentioning

confidence: 99%

Simulation of the scrape-off layer region of tokamak devices

Ricci

2015

J. Plasma Phys.

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“…We would like to remark that a fluid description of the SOL dynamics with a model based on the Braginskii equations may be limited to low-temperature regimes such as the L-mode. In fact, high-temperature events such as the edge localized modes (ELMs) observed in H-mode plasmas [23] may require more sophisticated fluid closures [24]. For the sake of simplicity, we consider a tokamak SOL with circular magnetic flux surfaces, no magnetic shear and a large aspect ratio.…”

Section: The Gbs Modelmentioning

confidence: 99%

Effect of the limiter position on the scrape-off layer width, radial electric field and intrinsic flows

et al. 2014

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The effect of the limiter position on the scrape-off layer (SOL) width, radial electric field and intrinsic flows is investigated via global, three-dimensional turbulence simulations in four different limiter configurations. The limiter position affects the SOL dynamics in a number of ways, for example by changing the effective connection length or by modifying the unstable modes present in the system. The simulations show that the SOL width is much smaller and less poloidally asymmetric when the plasma is limited on the low-field side than on the high-field side, which can be explained by a change in the turbulence regime between the two configurations. The radial electric field is determined by the combined effect of the sheath physics and the electron adiabaticity condition, and its poloidal structure depends on the limiter position, as it can be fairly well explained through an analytical model. Intrinsic parallel flows established in the SOL, typically leading to co-current toroidal rotation with a magnitude that strongly depends on the limiter position, can also be fairly well reproduced analytically for each limiter configuration.

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“…In fact, high-temperature events, such as the Edge Localized Modes (ELMs) observed in H-mode plasmas, 29 may require more sophisticated fluid closures. 30 As an example, we consider here the result of a simulation of SOL electrostatic turbulence in the simplest case of circular magnetic flux surfaces and a toroidal limiter on the high field side (Figure 1). The corresponding equations solved by GBS are shown in Appendix A, together with the magnetic presheath boundary conditions imposed at the end of the field lines.…”

Section: Intrinsic Flows In Sol Simulationsmentioning

confidence: 99%

“…We conclude this section by discussing the main possible sources of discrepancy between the simulated Mach number and its theoretical prediction given by Eq. (30). First, the equilibrium component of the radial momentum flux, Eq.…”

Section: Comparison With Sol Turbulence Simulationsmentioning

confidence: 99%

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Intrinsic toroidal rotation in the scrape-off layer of tokamaks

et al. 2014

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The origin and nature of intrinsic toroidal plasma rotation in the scrape-off-layer (SOL) of tokamaks is investigated both analytically and through numerical simulations. It is shown that the equilibrium poloidal E Â B flow, the sheath physics, and the presence of poloidal asymmetries in the pressure profile act as sources of momentum, while turbulence provides the mechanism for the radial momentum transport. An equation for the radial and poloidal dependence of the equilibrium parallel ion flow is derived, and a simple analytical solution is presented. This solution reproduces and explains the main experimental trends for the Mach number found in the SOL of tokamaks. Global, three-dimensional fluid simulations of SOL turbulence in different limiter configurations confirm the validity of the analytical theory. [http://dx

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Non-local approach to kinetic effects on parallel transport in fluid models of the scrape-off layer

Cited by 38 publications

References 25 publications

Simulation of the scrape-off layer region of tokamak devices

Simulation of the scrape-off layer region of tokamak devices

Effect of the limiter position on the scrape-off layer width, radial electric field and intrinsic flows

Intrinsic toroidal rotation in the scrape-off layer of tokamaks

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