Abstract Details
Abstracts
Author: Donald A Spong
Requested Type: Poster
Submitted: 2023-03-30 13:23:15
Co-authors: A. Bader, J. Varela, Y. Ghai, L. Garcia
Contact Info:
Oak Ridge National Laboratory
1 Bethel Valley Road
Oak Ridge, Tennessee 37831
U.S.A.
Abstract Text:
Energetic particle (EP) driven instabilities are a concern in fusion systems since they can degrade plasma heating efficiencies and lead to damage of plasma facing components. Stellarators have demonstrated an ability to access higher density regimes than tokamaks; high density can in principle mitigate the influence of EP driven instabilities by decreasing the slowing-down time which then decreases the energy density of EP components. A study is made of this effect based on linear stability calculations using the FAR3d gyrofluid model. Applications are made to the high magnetic field Wistell-D quasi-helical reactor configuration. The plasma electron density and temperature are varied subject to the constraint of constant fusion power output. EP instability growth rates are calculated, based upon EP densities and effective temperatures determined from a slowing-down model. With increasing density, a range of EP instabilities at different toroidal mode families approach marginal stability. Initial results indicate that the steady-state, full power regime may be protected from larger scale EP instabilities if the plasma density is above ~3 x 10^20 m^-3. The start-up trajectory of the reactor will need further analysis in the future as it may transiently pass through EP unstable regimes.
Acknowledgements - This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under Award DE-AC05-00OR22725, and the U.S. DOE SciDAC ISEP Center.
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