In this paper we study the simple case of the dynamics of a density perturbation localized in the edge region of a medium sized tokamak in a full 3D geometry. The 2D evolution of such a perturbation has been studied in details on the low-field side, where the gradient of the magnetic field always point radial inward, see e.g. [1-2]. Here, the initial condition is implemented in two very different 3D numerical codes, ATTEMPT , and a new developed code, DIESEL (Disk version of ESEL), and the results are compared and discussed in detail. The ATTEMPT code has been employed to study the blob dynamics in a full 3D tokamak geometry including the edge and SOL region as well. Previous studies with the ATTEMPT code proved that density blobs appear for typical parameters in the TEXTOR tokamak. The code has been prepared for flux driven simulations with detailed control of the blob initial state. The DIESEL code is an extension of the ESEL code . It solves a simple interchange model in full 3D tokamak geometry, where the toroidal direction is divided into a number of drift planes. On each drift plane the equations are solved in a domain corresponding to the full 2D cross section of the tokamak and communicate parallel with the nearest drift planes using parameterized velocities, the ion sound speed, Cs for the density equation and the Alfvén speed VA for the vorticity equation. Results show that a decrease of Alfvénic interaction of electric potential and current density leads to the expected radial blob motion. This is to be expected in the SOL and the first results are in agreement with previous studies,  based on simplified 2d-models and approximate closures for the Alfvénic interaction. The work aims at a detailed understanding of the dependence of blob motion on collisionality and SOL boundary conditions at the plasma material boundaries.
|Publication status||Published - 2008|
|Event||13. EU-US TTF workshop 2008 and 1. EFDA Transport Topical Group meeting - Copenhagen (DK), 1-4 Sep|
Duration: 1 Jan 2008 → …
|Conference||13. EU-US TTF workshop 2008 and 1. EFDA Transport Topical Group meeting|
|City||Copenhagen (DK), 1-4 Sep|
|Period||01/01/2008 → …|