Imaging key aspects of fast ion physics in the DIII-D tokamak

M. A. Van Zeeland, J. H. Yu, W. W. Heidbrink, N. H. Brooks, K. H. Burrell, M. S. Chu, A. W. Hyatt, C. Muscatello, R. Nazikian, N. A. Pablant, D. C. Pace, W. M. Solomon, M. R. Wade

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Visible imaging has been used to provide the 2D spatial structure and temporal evolution of the profile of highenergy neutrals introduced by neutral beam injection, the fast ion profile and a variety of plasma instabilities in DIII-D plasmas; the combination of these techniques form a comprehensive fast ion physics diagnostic suite. The injected neutral profile is imaged in Doppler shifted Dα light induced by collisional excitation. Fast ion profile information was obtained through imaging of Doppler shifted fast ion Dα light (FIDA) emitted by re-neutralized energetic ions. Imaging of FIDA emission during sawtooth events shows a large central depletion following sawtooth crashes-indicative of a broad redistribution of fast ions. Two examples of instability structure measurements are given. Measurements of the detailed 2D poloidal structure of rotating tearing modes were obtained using spectrally filtered fast imaging of broadband visible bremsstrahlung emission, a method which is capable of imaging with high resolution the structure of coherent oscillations in the core of current and next-step fusion plasma experiments and can be applied to virtually any mode with a finite perturbed bremsstrahlung emissivity and frequency in the laboratory frame. Measurements are also presented of the n = 0 energetic particle geodesic acoustic mode which were made by observing fluctuations in active emission.

Original languageEnglish
Article number084002
JournalNuclear Fusion
Volume50
Issue number8
DOIs
StatePublished - Aug 2010
Externally publishedYes

Fingerprint

Dive into the research topics of 'Imaging key aspects of fast ion physics in the DIII-D tokamak'. Together they form a unique fingerprint.

Cite this