Runaway electron transport via tokamak microturbulence

Hauff, T.; Jenko, F.

doi:10.1063/1.3243494

Cited by 24 publications

(39 citation statements)

References 16 publications

(22 reference statements)

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“…The magnetic fluctuations of interest tend to be nearly static on the electron transit time-scale, and the resulting heat diffusion coefficient should then be proportional to the electron thermal speed and scale as δ B ( ) 2 with the perturbation level. There has been an extensive work aimed at modeling and deeper understanding of the field stochastization and its consequences [9], [10], [11], [12], [13], [14]. One of the noteworthy outcomes is that the contribution of the very short wavelengths perturbations to transport is relatively small as a result of averaging along the guiding center orbit or full gyro-orbit.…”

Section: Critical Role Of Bulk Electron Coolingmentioning

confidence: 99%

Kinetics of relativistic runaway electrons

Breǐzman

Aleynikov

2017

Nucl. Fusion

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This overview covers recent developments in the theory of runaway electrons in tokamaks. Its main purpose is to outline the intuitive basis for first-principle advancements in runaway electron physics. The overview highlights the following physics aspects of the runaway evolution: (1) survival and acceleration of initially hot electrons during thermal quench, (2) effect of magnetic perturbations on runaway confinement, (3) multiplication of the runaways via knock-on collisions with the bulk electrons, (4) slow decay of the runaway current, and (5) runaway-driven micro-instabilities. The scope of the reported studies is governed by the need to understand the behavior of runaway electrons as an essential physics element of the disruption events in ITER in order to develop an effective runaway mitigation scheme.

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Section: Critical Role Of Bulk Electron Coolingmentioning

confidence: 99%

Kinetics of relativistic runaway electrons

Breǐzman

Aleynikov

2017

Nucl. Fusion

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“…The full 3D simulation with ASCOT required approximately 600 cpu-hours while only a few minutes were needed with the 1D-model. model, (11), were already shown in Fig. 4.…”

Section: Comparison Of 1d-model To Full 3d Simulationsmentioning

confidence: 57%

An advection–diffusion model for cross-field runaway electron transport in perturbed magnetic fields

Särkimäki

Hirvijoki²,

Decker

et al. 2016

Plasma Phys. Control. Fusion

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Disruption-generated runaway electrons (RE) present an outstanding issue for ITER. The predictive computational studies of RE generation rely on orbitaveraged computations and, as such, they lack the effects from the magnetic field stochasticity. Since stochasiticity is naturally present in post-disruption plasma, and externally induced stochastization offers a prominent mechanism to mitigate RE avalanche, we present an advection-diffusion model that can be used to couple an orbit-following code to an orbit-averaged tool in order to capture the crossfield transport and to overcome the latter's limitation. The transport coefficients are evaluated via a Monte Carlo method. We show that the diffusion coefficient differs significantly from the well-known Rechester-Rosenbluth result. We also demonstrate the importance of including the advection: it has a two-fold role both in modelling transport barriers created by magnetic islands and in amplifying losses in regions where the islands are not present.

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“…Using Eq. (7) and assuming that w n w and n max ) n min , one can obtain the following estimation: (8). The latter is plotted in Fig.…”

Section: B a Specific Model Of Modesmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8]. Understanding this problem is of crucial importance in modern fusion devices.…”

Section: Introductionmentioning

confidence: 99%

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New mechanism of runaway electron diffusion due to microturbulence in tokamaks

2012

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Chaotic transport of runaway electrons in a toroidal system in the presence of a weak small-scale magnetic turbulent field with a wide mode spectrum is studied. Using a fast running mapping, the radial profiles of turbulent diffusion coefficients are calculated. It is found that at large Kubo numbers the chaotic transport of the electrons is described by a fractal-like radial dependence of the diffusion coefficients with reduced or zero values near low-order rational drift surfaces which form transport barriers. The latter can be one of the main reasons of the improved confinement of runaway electrons in tokamaks. One can expect that this effect may lead to the formation of the nested beams of runaway electrons. [http://dx

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Runaway electron transport via tokamak microturbulence

Cited by 24 publications

References 16 publications

Kinetics of relativistic runaway electrons

Kinetics of relativistic runaway electrons

An advection–diffusion model for cross-field runaway electron transport in perturbed magnetic fields

New mechanism of runaway electron diffusion due to microturbulence in tokamaks

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