The application of the first integrated simulation tools to fusion machines marks a milestone for the EFDA Integrated Tokamak Modelling Task Force. At its annual meeting in Garching, the Task Force introduced the prototype tools to a wider community of modellers.

“Our tools are like LEGO® bricks. They plug into each other and allow a modeller to build a physics simulation according to his or her needs”. Denis Kalupin, EFDA Responsible Officer for the Integrated Tokamak Modelling (ITM) Task Force, sums up what his work is all about. ITM develops a set of generic modelling tools, which simulate the behaviour of plasmas in any fusion machine or for any specific problem. “Some modules run very fast for quick and rough simulations and others zoom into details in space or time. For each problem, scientists would normally have to adapt different numerical codes and couple them together by designing an individual interface. Within the ITM environment this switch between fast, simple solutions and slower, more sophisticated ones is extremely easy.”

First physics results

Plasma modellers from all over Europe contribute to the development and validation of the ITM plasma simulator. Its major component is the European Transport Solver (ETS), which will allow scientists to simulate transport processes in a tokamak plasma within a unique modular package. The Task Force organises regular “code camps”, where developers meet for two weeks of concentrated work. “Each code camp brings us a big step further” explains ITM Task Force Leader Gloria Falchetto, “While participants adapt their modules to the ITM infrastructure and integrate them into the ETS, they share experiences and many issues are solved much more quickly this way.“ The ETS has been released internally to ITM members for verification and optimisation. A first public version will be out next year. A subroutine of the ETS, the equilibrium reconstruction and stability simulation chain is already available for general use. The chain allows the setup of a magnetic field configuration and the determination of the plasma stability. It has produced first physics results for ASDEX Upgrade and ITER discharges. The equilibrium reconstruction module is already in use at Tore Supra and JET.

The ITM Task Force has progressed substantially in the last seven years. In some areas it has produced tools that are used today by the EFDA Associates. Now it is time to take stock of this experience in order to strengthen the competitiveness of European modellers towards ITER through a more efficient organisation of these activities.

EFDA-Leader Francesco Romanelli

Automated protection for ITER

The meeting also addressed the coupling of modules describing the edge and core of the plasma, synergetic effects between the various heating sources and issues regarding the plasma control. Lively discussion surrounded the standardisation of interfaces in order to include diagnostic signals for the plasma control systems into the plasma simulator. This will develop the ETS towards one of the ultimate needs of ITER, which is a transport simulator linked to the plant control system. Wayne Houlberg, Head of the ITER Integrated Modelling Expert Group, explains: “We are pushing ITER to the limits, where we get maximum performance and still operate safely. The simulation will have to tell us automatically whether the control systems can maintain the parameters needed for the planned plasma pulse.”