After a reminder of basic notions of fusion and magnetic confinement of plasmas, the talk will present results and plans from the European start-up Renaissance Fusion.
The company synergistically combines three main pillars: the stellarator, High Temperature Superconductors (HTS) and liquid metal walls. The stellarator magnetically confines fusion plasmas similarly to a tokamak, but without needing a current in the plasma. As a result it is more stable and inherently steady-state, but requires more complicated external coils. At Renaissance Fusion we dramatically simplify the coils by (1) finding solutions on simplified coil-winding-surfaces and by (2) streamlined manufacturing. Tapes and cables are bypassed. Instead, multiple layers of HTS material are directly deposited on the vacuum vessel or other wide surfaces, and patterned to impose specific supercurrent paths that generate stellarator magnetic fields. Both simplifications (1) and (2) pose interesting mathematical problems, for instance in inverse problems and optimization. Mesoscale liquid metal walls shield the stellarator and delicate HTS from neutrons and make them less radioactive. Experimental evidence will be presented of free-surface liquid metal flows adhering to the interior of cylindrical chambers by means of electromagnetic and centrifugal forces. Passive and active magnetohydrodynamic stabilization was obtained, as well as initial results toward feedback stabilization. Additional optimization results will be presented in the areas of coil force minimization, neutronic optimization of plasma-facing liquid metal walls, the design point of a profitable reactor and, in the shorter term, next-step HTS stellarator experiments. Paradigm-shifting ways of extracting Tritium will be presented. Research needs, job openings and areas of possible collaboration will also be discussed.
Francesco A. Volpe is a fusion plasma physicist turned entrepreneur. He studied and conducted his research in Italy (Laurea 1998), Germany (PhD 2003), the UK and USA (post-docs ended in 2008). From 2009 to 2019 he held academic appointments at the University of Wisconsin, Madison, and at Columbia University, in New York, where he reached the rank of Associate Professor in 2015. Francesco conducted research on all four major magnetic confinement fusion concepts (tokamaks, spherical tokamaks, stellarators and reversed field pinches), making contributions to the physics of Electron Bernstein Waves, avoidance of tokamak disruptions, simplification of stellarators and control of liquid metal walls.
He received the 2003 Otto Hahn Medal (thesis prize of the Max Planck Society), the 2011 DOE Early Career Award and the 2015 Excellence in Fusion Engineering Award by Fusion Power Associates. In 2019 he earned an Executive MBA at ESCP Europe and in 2020 he founded the first magnetic fusion start-up in continental Europe and one of only two stellarator start-ups in the world: Renaissance Fusion.