On energetic particles

The 2023 ITER International School gathered 160 participants from 26 different countries, representing a diverse and international community of experts in the field. The lectures were delivered by 13 prominent specialists in the field of energetic particle physics in magnetic fusion devices.

The ITER International School was the 12th in the series, which alternates between sites in Aix-en-Provence, in the south of France, close to where ITER is being constructed, and external hosts within the ITER Member countries. This time, after a hiatus due to Covid, the school took place at the Faculty of Law Campus in Aix-en-Provence, which provided excellent logistical support and facilities for the participants. A notable contribution to the success of the school was made by Aix-Marseille University, which not only provided financial support but also played a crucial role in hosting the event.

The subject of this year's school focused on the impact and consequences of energetic particles on fusion plasmas, a particularly relevant multidisciplinary topic for ITER whose missions rely upon successfully harnessing the power released in the form of energetic alpha-particles to sustain a self-heating plasma.  Energetic particles are created by auxiliary heating systems (radiofrequency heating and neutral-beam injection), fusion reactions and (in the case of runaway electrons) electric fields parallel to the magnetic field.

Interactions between the energetic particles and the magnetic fields can lead to instabilities that can modify the field itself and the energetic particles' distributions (density and energy). At the school, approaches to understanding this interaction to various levels of complexity were presented and discussed. This ranged from linear approaches near marginal stability to complex nonlinear simulations which explain many observations of energetic particle-driven instabilities and allow a deeper understanding of the interactions taking place. A deeper understanding of the physics of particular instabilities also opens the door to future advanced control opportunities to mitigate the consequences in terms of energetic particle transport and loss.

The school also discussed diagnostic methods and interpretation techniques that enable the consequences of plasma instabilities driven by energetic particles to be quantified in terms of particle transport and loss. While most of the material presented at the school focused on energetic ions, energetic electrons were not neglected. In particular the physics of so-called runaway electrons that can reach relativistic speeds in the presence of an accelerating electric field were introduced, together with experimental observations and detailed modelling.

At the school, leading experts in the field of energetic particle physics provided many hours of lectures on the interlinked multidisciplinary topics outlined above. This was complemented with a combination of worked examples, tutorials and quizzes, that allowed the participants to gain a deeper understanding of the many facets of energetic particle physics.  

One of the highlights of the school was a visit to the ITER construction site. This opportunity allowed participants to witness first-hand the progress and advancements being made in the field of fusion energy. It provided valuable insights and a deeper understanding of the practical aspects of the research being conducted. In addition to the visit to the ITER site, the school also featured three lectures given in the auditorium of ITER Headquarters. These lectures, delivered by prominent ITER experts, offered participants a unique opportunity to learn from and interact with leaders in the fusion energy community.

Overall, the 12th ITER International School was a resounding success, bringing together a diverse group of participants from around the world to exchange knowledge, share experiences, and foster collaboration in the field of energetic particles and fusion plasma. The support from Aix Marseille University, the ITER Organization, the US Burning Plasma Organization and the International Atomic Energy Agency (IAEA) greatly contributed to the success of this event.

The slides of the 2023 lectures are available on this ITER webpage, together with information on past ITER International Schools.