Active Beam Spectroscopy for control of the fusion plasma

Over the past three decades the use of active neutral beams injected into a fusion relevant plasma has developed into a powerful diagnostic technique to obtain local values of the main ion features: ion temperature, rotation and ion density. Now a new era is entered with the development of the first net energy producing fusion reactor: ITER. In this device the diagnostic information forms the basis of several control loops for the plasma operation. Expertise, in the past provided by spectroscopists, should now be broadened towards engineers (for the control algorithms), atomic physicists (for the quantitative interpretation of the spectral measurement), plasma physicists (for the physics mechanisms involved) etc. Apart from that, still new applications of active beam spectroscopy in fusion devices are being assessed. The monitoring of the fast alpha particles produced in a fusion process is the newest challenge that has come into reach of the new diagnostic capabilities.

Since the opportunities for the gathering of those various disciplines are limited, it is the aim of this workshop to bring together these experts sharing an interest in the newest developments as well as in the application of the active beam spectroscopy for fusion devices. The focus of the workshop is concentrated around the fields that have a direct impact on the active beam spectroscopy for the experimental fusion reactor ITER:

-          Real time control and data-analysis

-          Atomic data needs

-          Instrumental developments

-          Experience from existing fusion devices

-          Beam emission spectroscopy

-          Fast ion detection

-          Physics of burning fusion plasmas and diagnostic needs for ITER

The motivation of a workshop-type gathering is at least twofold. First, it is timely, since options for the exact definition and use on ITER are still open. For ideas having impact on the design or performance of the system for ITER it is just timely to be included in the present ITER activity. Second, the workshop is partly intended as a tribute to Manfred von Hellermann, retiring immediately after the workshop. Ever since the first active beam spectra have been recorded he has recognized the importance of this technique and pushed the further development of it, culminating into the inclusion into the ITER project. He acted as chairman of the international effort on active beam spectroscopy for the past 10 years. In this respect, the workshop can be seen to hand over the present expertise in this field to the next generation to apply it on fusion plasma. It was found most appropriate to organize this event as a more informal workshop.

The anticipated outcome of the workshop would be to come up with an integrated strategy to prepare for the application of active beam spectroscopy on ITER. Collaborations between the different fields should be encouraged and concretized during the workshop, resulting in clear deliverables and research programmes compatible with the overall strategy.