Stabilization of Alfvén Eigenmodes in DIII-D via Controlled Energetic Ion Density Ramp and Validation of Theory and Simulations
Shawn Tang, Troy Carter, N. A. Crocker, W. W. Heidbrink, Jeff Lestz, R. I. Pinsker, K. E. Thome, M. A. Van Zeeland, E. V. Belova
Abstract
Fast-ion driven Alfvén waves with frequency close to the ion cyclotron frequency (f=0.58f_{ci}) excited by energetic ions from a neutral beam are stabilized via a controlled energetic ion density ramp for the first time in a fusion research plasma. The scaling of wave amplitude with injection rate is consistent with theory for single mode collisional saturation near marginal stability. The wave is identified as a shear-polarized global Alfvén eigenmode excited by Doppler-shifted cyclotron resonance with fast ions with sub-Alfvénic energetic ions, a first in fusion research plasmas.
Topics & Concepts
Atomic physicsDIII-DPhysicsIonExcited stateCyclotronAmplitudeDoppler effectPlasmaIon cyclotron resonanceTokamakNuclear physicsOpticsAstronomyQuantum mechanicsMagnetic confinement fusion researchIonosphere and magnetosphere dynamicsSolar and Space Plasma Dynamics