Blob interactions in 2D scrape-off layer simulations
- 1 December 2020
- journal article
- research article
- Published by AIP Publishing in Physics of Plasmas
- Vol. 27 (12), 122301
- https://doi.org/10.1063/5.0021314
Abstract
Interaction of coherent structures known as blobs in the scrape-off layer of magnetically confined plasmas is investigated. Isolated and interacting seeded blobs, as well as full plasma turbulence, are studied by two-dimensional numerical simulations. The features of the blobs (position, size, amplitude) are determined with a blob tracking algorithm, which identifies them as coherent structures with amplitudes above a chosen particle density threshold, and their velocities are compared to a conventional center of mass approach. We find that the theoretical velocity-size scaling dependence for isolated blobs is correctly resolved by the blob tracking method. The benchmarked approach is then extended to a population of interacting plasma blobs with statistically distributed amplitudes, sizes, and initial positions for different levels of blob interaction. We observe a correlation between the level of blob interaction and the number of blobs deviating from size–velocity scaling laws of perfectly isolated blobs. This is found to be caused by the interaction of blobs with the electrostatic potential of one another, leading to higher average blob velocities. We introduce a model specific intermittency parameter, quantifying the degree of blob interaction. For interacting blobs, we estimate the deviation from the picture of perfectly isolated blobs as a function of the intermittency parameter. For full plasma turbulence simulations, we observe a strong correlation between the blob amplitudes, sizes, and velocities estimated by the blob tracking algorithm.Keywords
Funding Information
- Engineering and Physical Sciences Research Council (EP/T012250/1)
- FP7 Fusion Energy Research (633053)
- UiT Aurora Centre Program
- CINECA Marconi supercomputer within FUA34_SOLBOUT4 (633053)
This publication has 74 references indexed in Scilit:
- Inter-ELM filaments and turbulent transport in the Mega-Amp Spherical TokamakPlasma Physics and Controlled Fusion, 2009
- Experiments and simulation of edge turbulence and filaments in MASTPlasma Physics and Controlled Fusion, 2008
- Collisionality dependent transport in TCV SOL plasmasPlasma Physics and Controlled Fusion, 2007
- Fluctuations and transport in the TCV scrape-off layerNuclear Fusion, 2007
- Filament structures at the plasma edge on MASTPlasma Physics and Controlled Fusion, 2006
- Transport by intermittency in the boundary of the DIII-D tokamakPhysics of Plasmas, 2003
- Universality of intermittent convective transport in the scrape-off layer of magnetically confined devicesPhysics of Plasmas, 2003
- Fluctuation-driven transport in the DIII-D boundaryPlasma Physics and Controlled Fusion, 2002
- Transport by intermittent convection in the boundary of the DIII-D tokamakPhysics of Plasmas, 2001
- Experimental Evidence of Intermittent Convection in the Edge of Magnetic Confinement DevicesPhysical Review Letters, 2001