DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 99: Establishment of a database for EMC3/EIRENE benchmark and direct comparison to TEXTOR (1) | ||
| Name: | Oliver Schmitz ( |
Affiliation: | FZ Juelich |
| Research Area: | Thermal Transport in the Plasma Boundary | Presentation time: | Not requested | Co-Author(s): | Heinke Frerichs (FZ Juelich), Marcin Jakubowski (MPI Greifswald), Bernhard Unterberg (FZ Juelich), Todd Evans (GA), Max Fenstermacher (LLNL), Ilon Joseph (UCSD), Rick Moyer (UCSD), Detlev Reiter (FZ Juelich) |
| Description: | For the analysis of energy and particle transport the fully 3D Monte-Carlo code EMC3/EIRENE is under adaptation to work for poloidally diverted tokamak geometries. The aim is to resolve the role of open, perturbed magnetic field lines for the transport changes and the pedestal pressure drop in RMP ELM control experiments. Hereto, since November 2006, a consistent experimental and theoretical approach is under execution in the frame of an IAE collaborative agreement between DIII-D and TEXTOR and an accompanying ITPA task (PEP-19) on collaborative experiments. The EMC3/EIRENE code is together with magnetic modelling tools the binding element between the experiments and it plays a key role for the comparison of the results. As so far this code was applied only in stellarator symmetry and in circular TEXTOR plasmas with non- axis symmetric perturbation, the code need to be adapted and improved for proper transport analysis at DIII-D in a poloidally diverted configuration. The aim of this experimental proposal is to establish a coherent data base to benchmark the code on the one hand and to tackle simultaneously generic physical questions during this benchmark shots on the other hand. This proposal is part of a coherent benchmark and analysis plan. Another proposal is submitted under TF ELM control. Both contain the complete list of shots to be performed creating a good benchmark data base on the one hand and simultaneously tackling basic physical issues. | ||
| Experimental Approach/Plan: | We intend to go from L-mode and H-mode plasmas in the limiter configuration - which will be compared to accompanying discharges at TEXTOR-DED - to the poloidally diverted configuration. Here also L-mode discharges will be the start point to be able finally tackling the poloidally diverted ELM suppressed H-mode discharges as ultimate target of analysis.
For best understanding we would like to do these different discharges each with toroidal mode number (in order of priority) n=3, n=2 and n=1. The n=2 configuration is also available at TEXTOR-DED and a prominent example for comparison to the JET results. Also to gain information on the collisionality on the transport and the description by the code (e.g. fluid limits in the conductive heat transport) we will do each discharge for low and for high collisionality. We will rely for the design of each discharge on the best settings from the RMP experience at DIII-D. For those discharges not done for longer time (limiter L-mode, but with tiny beam for CER) we need some development. In summary we will need the following set of discharges for both, low and high collisionality: - limiter L-mode (n=3,2,1 each with reference as different error field (EF) situation) - limiter H-mode (n=3,2,1 each with reference as different EF situation) - divertor L-mode (n=3,2,1 each with reference as different EF situation) - divertor L-mode, repeat shots with different filter settings on cameras -> get electron parameters from line ratios and impurity behaviour - sweeps in divertor L-mode for enhancement of diagnostic coverage (e.g. LP on target) (n=3,2,1 each with reference as different EF situation) - divertor H-mode (samples as good data base is existing, we intend to have corresponding samples to shots defined above for L-mode) This would be the ideal set of discharges. However, the base mode numbers are mentioned in order of priority and it is more important to have one complete scan for one base mode than having single shots for different base modes. For this task force especially the no-RMP discharges will contribute from the experimental point and also the shots with good diagnostic coverage can shed light to the particle and heat flux redistribution in the divertor. The EMC3/EIRENE modell is capabel to describe and study that. | ||
| Background: | The proposal described here is embedded in the ITPA inter machine experiments for investigation on the impact on RMP on particle and heat transport and the extrapolation towards ITER. It has three major topics which are combined in the establishment of a comprehensive database for the EMC3/EIRENE code benchmark after the adaptation is finished. The set of discharges described enables us to check the adapted version for general consistency (properly implemented poloidally diverted field aligned grid) and also to resolve the adaptations needed for the transport description. So far the anomalous perpendicular transport is described in EMC3/EIRENE as one input parameter in the whole radial modelling domain. There shall be the need to improve this and replace this radial constant by a radial function. In addition the discharges suggested allow analysis not done so far in particular in comparison to TEXTOR-DED. The role of the open, perturbed field lines in the magnetic flux loss region was elaborated here and it was shown that short field lines connecting to the wall are of dominant impact for the static and turbulent transport processes. This shall be resolved for DIII-D with these experiments as we will perform discharges in limiter configuration comparable to TEXTOR-DED and do a correspondent analysis on this topic for L-mode and H-mode discharges with RMP of different base modes. The experimental data will be compared to the magnetic topology modelled with the TRIP-3D code and eventually the transport is analyzed with the adapted EMC3/EIRENE code. During this procedure and based on this comprehensive database, the code shall be improved for a detailed analysis of the ELM suppression mechanism on both machines and for prediction to ITER. | ||
| Resource Requirements: | Limiter L- and H-mode plasmas, both with CER beam box, else are standard RMP requirements | ||
| Diagnostic Requirements: | standard RMP, in particular good CCD camera coverage (DiMES TV and tangential divertor TV systems), good IR camera coverage, fast probe operation, CER beam box, target Langmuir probes, pressure gauges, full Thomson scattering availability
In the frame of this proposal the mounting of a nozzle for parasitic He injection for beam emission spectroscopy (BES) is suggested. A low and non-disturbing flux of about 0.5e18 He atom s-1, is needed to obtain the line emission of three He lines. They are compared to a collisional radiative model of the related transitions and the electron density and temperature can be obtained with high radial and depending on the DAQ with high time resolution also. The technique itself was developed in FZ Juelich and is at TEXTOR-DED a reliable method to get these electron parameters in most of all TEXTOR discharges. The hardware equipment as well as the CRM needed for the evaluation and the experienced manpower to perform this task would be provided. | ||
| Analysis Requirements: | standard RMP requirements, kinetic EFIT runs for good equilibrium data for magnetic modelling and field aligned grid production, 2D transport analysis with the [onetwo code] or results from the [SOLPS5/EIRENE] effort started recently to get good input for the anomalous diffusion coefficients and ideas about the radial function of these input parameters | ||
| Other Requirements: | -- | ||
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