Plasma Physicists from the Institute for Fusion Studies (IFS) at the University of Texas, The Graduate School of Mathematical Sciences at the University of Tokyo, and private fusion leader ExoFusion have developed a unified theory of transport barriers in magnetically confined systems, published in Nuclear Fusion, Sept 17th. The paper can be found here.
If we can exploit the ability of transport barriers to drastically reduce turbulent heat loss, then the advent of Commercially Viable Fusion (CVF) will be hastened.
To create the "best" barrier conditions, we must understand the physics that underwrites this remarkable state and then work to create the conditions such that this physics can prevail.
The paper significantly addresses this formidable challenge by constructing a coherent physical picture of transport barrier formation that spans the macroscopic thermodynamic (ThTB) and microscopic (MTB) descriptions. Qualitatively, it depends on a central insight: when incoming heat flux is channeled preferentially into coherent flows (rather than dissipated through turbulent diffusion), the system naturally sustains a high-gradient state (the defining criterion of good confinement). This is an elegant and succinct way to frame what is otherwise a sprawling and technically intricate body of work.
The paper then demonstrates—via an elementary macroscopic predictive model calculation coupled to and supported by the immense body of knowledge acquired through detailed microscopic simulations and experiments- how to characterize the barrier including what factors help its formation and sustenance and what knobs must be turned to achieve the desired state.
The results exemplify an elegant physical principle found to successfully explain how several physical systems organize into coherent states. The principle is called “Maximum Entropy Production” (MEP).
This macro-micro synthesis is a unique and powerful contribution, suggesting a variety of new experiments that can equip the community to pursue CVF with greater confidence and a higher chance of success.
According to Dr. Diego del-Castillo Negrete, Director of the Institute for Fusion Studies, “By connecting a macroscopic thermodynamic model with microscopic transport-barrier theory this paper advances understanding of the formation and maintenance of transport barriers—a fundamental problem in magnetically confined fusion plasmas.”
Lead author Dr. Swadesh Mahajan, of both IFS and ExoFusion, adds, “We believe this work to be fundamental to confinement and therefore to the pursuit of Commercially Viable Fusion. We continue to believe that innovative science, in conjunction with great engineering, is key to this grand pursuit.”
ExoFusion is an innovative company focused on accelerating the path to Commercially Viable Fusion (CVF). ExoFusion is a leader in the physics and technologies of confinement of novel materials for the first wall. ExoFusion focuses on design, simulation, IP, and scientific innovation for growing Fusion industry. ExoFusion is a recipient of ARPA-E, SCIDAC, FIRE, INFUSE and other grants. The company works across device types and fuel cycles.
SOURCE: ExoFusion