Evidence for suprathermal ion distribution in burning plasmas
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21ja116_full.pdf
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Author(s)
Hartouni, E.P.
Moore, A.S.
Crilly, A.J.
Appelbe, B.D.
Amendt, P.A.
Baker, K.L.
Casey, D.T.
Clark, D.S.
Döppner, T.
Eckart, M.J.
Date Issued
June 2021
Journal
Nature Physics
Publisher
Nature
Abstract
At the National Ignition Facility, inertial confinement fusion experiments aim to burn and ignite a hydrogen plasma to generate a net source of energy through the fusion of deuterium and tritium ions. The energy deposited by α-particles released from the deuterium–tritium fusion reaction plays the central role in heating the fuel to achieve a sustained thermonuclear burn. In the hydrodynamic picture, α-heating increases the temperature of the plasma, leading to increased reactivity because the mean ion kinetic energy increases. Therefore, the ion temperature is related to the mean ion kinetic energy. Here we use the moments of the neutron spectrum to study the relationship between the ion temperature (measured by the variance in the neutron kinetic energy spectrum) and the ion mean kinetic energy (measured by the shift in the mean neutron energy). We observe a departure from the relationship expected for plasmas where the ion relative kinetic energy distribution is Maxwell–Boltzmann, when the plasma begins to burn. Understanding the cause of this departure from hydrodynamic behaviour could be important for achieving robust and reproducible ignition.
Description
Submitted for publication in Nature Physics
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1038/s41567-022-01809-3
