Theoretical understanding of the Isotope Effects in Tokamak Plasmas: Core and Edge

Recently, a flurry of activities has been carried out on the isotopic effects in JT-60U [1], JET [2] and DIII-D [3], which has shown favorable confinement trend for heavier hydrogen isotopes. The consensus from these experimental observations was that this is an unsolved puzzle in tokamak plasmas. This is in fact not correct. When the favorable effects was first observed on TFTR [4] for hydrogen, deuterium and tritium experiments, a theoretical attempt was indeed proposed to understand the results by Lee and Santoro [5]. Apparently, this paper has not attracted much attention in the community. Moreover, a paper by Lee and White [6] on the H-mode has also reported on the isotope effects at the H-mode pedestal. In this presentation, the author will give the theoretical interpretations on these isotopic effects based on the resonance broadening theory [7] in the core as well as the force balance equation for the pedestal from the gyrokinetic theory [6]. The implementation of the the related physics in an initial value code such as GTC [8] will also be discussed.

[1] S. D. Scott, M. C. Zarnstorff, C. W. Barnes, R. Bell et al., Phys. Plasmas {f 2}, 2299 (1995)

[2] H. Urano and E. Narita , Plasma Phys. Control. Fusion {f 63}, 084003 (2021)

[3] L. Horvath, C. F. Maggi, A. Chankin et al., Nuclear Fusion {f 61}, 046015 (2021)

[4] L. Schmitz, Phil. Trans. R. Soc. {f A381}: 20210237 (2022)

[5] W. W. Lee and R. A. Santoro, Phys. Plasmas {f 4}, 169 (1997)

[6] T. H. Dupree, Phys. Fluids {f 11}, 2680 (1968)

[7] W. W. Lee and R. B. White, Phys. Plasmas {f 26}, 040701 (2019)

[8] H. Urano, Takizuka, N. Aiba, M. Kikuchi et al., Nucl. Fusion {f 53}, 083003 (2013)

Email: wwlee@pppl.gov