Professor Garbet’s principal accomplishments fall into six categories.
In the theory of turbulence spreading, he pointed out the possibility of bursty entrainment events, which de-localize turbulence relative to its point of excitation. This was a key initiator of the study of mesoscopic transport physics.
He has a leading role in the development of flux-driven simulations, both gyrokinetic and gyro-fluid. In particular, he inspired the building and exploitation of the GYSELA code, whose emphasis on flux-driven dynamics is unique among large gyrokinetic code efforts. The resulting significant review papers complement other notable reviews of gyrokinetics by their emphasis on physics interpretation.
He has made important contributions to internal transport barrier (ITB) physics to achieve improved confinement, where he led a Task Force of the JET programme in the early 2000s. He helped elucidate the role of resonant surfaces and magnetic shear in ITB formation. His scientific leadership was an important contribution to ITB confinement scenario development, a topic which is central to ITER.
A highlight of his excellent work clarifying and understanding the physics of ‘inward pinch’ processes relates to the up-gradient Turbulent Equipartition Pinch (TEP). The TEP, which is not thermodynamic, and is ultimately related to magnetic inhomogeneities, is the most robust and universal such process. He made important contributions to understanding the physics, by clarifying the relation between the TEP mechanism and the constraint of entropy production.
He has made important contributions to understanding plasma rotation and the transport of high-Z impurities, which radiate energy and trigger instabilities which are a major concern for the operation of magnetically confined plasmas. He unravelled synergistic interplays between collisional and turbulent transport, and highlighted mechanisms whereby experimentally observed spatial impurity distributions may be understood.
During the 1990s, he made important early contributions to understanding scrape-off layer (SOL) stability. He showed the possibility of interchange instability in the SOL, due to its magnetic structure, which links in turn to the key ITER physics issue of SOL width.