Active Beam Spectroscopy

for control of the fusion plasma

March 24-27, 2009

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 was 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 workshop was a big success, not only in this aspect. Almost all invited persons accepted the invitation to participate. Moreover, with a total of about 55 scientist of all over the world, the participation was about twice as big as originally anticipated. This resulted not only in lively discussions during the presentations, but more importantly, provided an excellent opportunity to have in-depth discussions in smaller circles. The Lorentz center is perfectly equipped for this. Several collaborations were concretized during this week, leaving some measurable results behind.

Apart from the scientific aims, the workshop was partly intended as a tribute to Manfred von Hellermann, who retired immediately after the workshop. Numerous colleagues in the field who collaborated over the years with him took this opportunity to express their sincere respect to Manfred and his scientific achievements. As a results of this, the atmosphere during the workshop was very relaxed and pleasant, being a meeting between friends, where the old generation transferred part of their expertise to the new generation. In this respect it is important to note that about 1/3 of the attendees where on a PhD or Postdoc level. This mix and combination of participants was regarded as essential for the success of the workshop. However, the most important reason for the success was undoubtedly the Lorentz center concept itself with its excellent facilities and extremely friendly and capable staff.

Roger Jaspers (FOM Rijnhuizen, The Netherlands)

Wolfgang Biel (Forschungszentrum Jülich, Germany)