The effect of species mix and fast-ion distribution on emission of fast magnetosonic waves near the ion cyclotron frequency
Abstract
In the radiation belts, energetic ions drive wave emission both above and below the ion cyclotron frequency ωci. In a Frontier Science experiment on the DIII-D tokamak, emission of fast magnetosonic waves near ωci and its harmonics is investigated using systematic scans of species mix, magnetic field, and fast-ion distribution function. For most fast-ion populations, increasing H+ in a background D+ plasma increases emission below ωci but decreases emission above ωci, while lower magnetic field strength gives stronger emission below ωci but has relatively little effect above ωci. Addition of a third species (3He++) sometimes introduces an additional emission band below ωci reminiscent of the three electromagnetic ion cyclotron wave bands of H+, He+, and O+ in space. For higher frequencies (ω>ωcH) fast magnetosonic waves with spectral peaks at multiples of ωcH have been observed by satellites in the equatorial magnetosphere. Similar spectra at harmonics of ωci are observed in magnetically confined fusion plasmas. Comparisons of stability calculations used in both the space and fusion communities will be shown.
Work supported by US DOE under DE-FC02-04ER54698.- Publication:
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APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..DPPTO8006V