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In this study, COGENT is a continuum gyrokinetic code for edge plasmas being developed by the Edge Simulation Laboratory collaboration. The code is distinguished by application of the fourth order conservative discretization, and mapped multiblock grid technology to handle the geometric complexity of the tokamak edge. It is written in v∥-μ (parallel velocity – magnetic moment) velocity coordinates, and making use of the gyrokinetic Poisson equation for the calculation of a self-consistent electric potential. In the present manuscript we report on the implementation and initial testing of a succession of increasingly detailed collision operator options, including a simple drag-diffusion operator in the parallel velocity space, Lorentz collisions, and a linearized model Fokker-Planck collision operator conserving momentum and energy (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Plasma blobs found in the edge region of tokamaks are important to understand because they contribute to a large amount of the plasma particle transport in the SOL (scrape off layer). Most of the work to date is limited to 2D theory and simulations by ignoring the variation of blob parameters along the magnetic field line. 3D effects are examined in the electrostatic limit in this paper using the code BOUT++ by allowing for the variation of blob density and potential along the field line. It is demonstrated that the 3D variation of these parameters can lead to a Boltzmann potential relation that will cause the blob to spin and induce turbulent motion via unstable drift waves (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)