Experimental measurements on DIII-D of hydrogen neutral penetration lengths ( ) on the high field side (HFS) are longer by a factor of than for deuterium consistent with the thermal velocity ratio for neutrals at the same temperature . This ratio is constant for both low and high pedestal electron density. At low pedestal density m , the neutral penetration length is greater than the density pedestal width for both isotopes, and the additional 40% increase of neutral penetration in hydrogen widens the pedestal by the same amount. As the density pedestal height increases m , the neutral penetration lengths drop below the density pedestal widths for both isotopes, and the increased penetration of hydrogen has no increased effect on the pedestal width compared to deuterium. Extrapolating to future reactor-relevant high electron density pedestals, the isotope-mass change in neutral fueling on the HFS from the deepest neutral penetration of hydrogen, to the shortest neutral penetration of tritium will be negligible (0.2–0.4 cm) in comparison to estimates of the density pedestal width (6–8.5 cm).
Chaban, R. A., et al. "The role of isotope mass on neutral fueling and density pedestal structure in the DIII-D tokamak." Nuclear Fusion, vol. 64, no. 4, Feb. 2024. https://doi.org/10.1088/1741-4326/ad2113
Chaban, R. A., Mordijck, S., Rosenthal, A. M., Bortolon, A., Hughes, J. W., Knolker, M., Laggner, F. M., Osborne, T. H., Schmitz, L., Thome, K. E., & Wilks, T. M. (2024). The role of isotope mass on neutral fueling and density pedestal structure in the DIII-D tokamak. Nuclear Fusion, 64(4). https://doi.org/10.1088/1741-4326/ad2113
Chaban, R. A., Mordijck, S., Rosenthal, A. M., et al., "The role of isotope mass on neutral fueling and density pedestal structure in the DIII-D tokamak," Nuclear Fusion 64, no. 4 (2024), https://doi.org/10.1088/1741-4326/ad2113
@article{osti_2311032,
author = {Chaban, R. A. and Mordijck, S. and Rosenthal, A. M. and Bortolon, A. and Hughes, J. W. and Knolker, M. and Laggner, F. M. and Osborne, T. H. and Schmitz, L. and Thome, K. E. and others},
title = {The role of isotope mass on neutral fueling and density pedestal structure in the DIII-D tokamak},
annote = {Abstract Experimental measurements on DIII-D of hydrogen neutral penetration lengths ( λ n 0 ) on the high field side (HFS) are longer by a factor of 2 than for deuterium consistent with the thermal velocity ratio for neutrals at the same temperature ( v t h H / v t h D = 2 ) . This ratio is constant for both low and high pedestal electron density. At low pedestal density ( n e ∼ 4 × 10 19 m − 3 ) , the neutral penetration length is greater than the density pedestal width for both isotopes, and the additional 40% increase of neutral penetration in hydrogen widens the pedestal by the same amount. As the density pedestal height increases ( n e ∼ 6 × 10 19 m − 3 ) , the neutral penetration lengths drop below the density pedestal widths for both isotopes, and the increased penetration of hydrogen has no increased effect on the pedestal width compared to deuterium. Extrapolating to future reactor-relevant high electron density pedestals, the isotope-mass change in neutral fueling on the HFS from the deepest neutral penetration of hydrogen, to the shortest neutral penetration of tritium will be negligible (0.2–0.4 cm) in comparison to estimates of the density pedestal width (6–8.5 cm). },
doi = {10.1088/1741-4326/ad2113},
url = {https://www.osti.gov/biblio/2311032},
journal = {Nuclear Fusion},
issn = {ISSN 0029-5515},
number = {4},
volume = {64},
place = {IAEA},
publisher = {IOP Publishing},
year = {2024},
month = {02}}
Field, A. R.; Chapman-Oplopoiou, B.; Connor, J. W.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 381, Issue 2242https://doi.org/10.1098/rsta.2021.0228