Princeton University Astrophysical Sciences Special Seminar

Collisional transport at the small collision frequencies characteristic of fusion reactors can be enormous in stellarators. In order to reduce this transport and the associated energy loss, the position and strength of the external magnets that produce the magnetic field in stellarators must be optimized. In this talk, I will revisit collisional transport in the particularly interesting limit of large aspect ratio stellarators. I will derive a new formulation to calculate collisional transport in the small collision frequency regime relevant to stellarator reactors. This new formulation has been implemented in KNOSOS (KiNetic Orbit-averaging SOlver for Stellarators), a very efficient, fast code that calculates collisional transport in a variety of regimes and can hence be used in stellarator optimization exercises. I will show both numerical and analytical results obtained using the new model that illustrate the nature of stellarator collisional transport at small collision frequencies.