Speaker
Dr
Sergei Sharapov
(CCFE)
Description
A systematic and significant recent effort in diagnosing energetic ion driven instabilities and related transport of the energetic ions on MAST is setting a stage for new understanding of such instabilities relevant to the next-step burning plasma experiment. The fast ion-driven Alfvenic instabilities are detected on MAST in the frequency range up to ~5 MHz with magnetic coils and with Doppler backscattering system. The fast ion population on MAST is represented by D NBI injected at Eb ≈ 60-70 keV, and it is studied with a four-channel neutron camera and energetic proton detector measuring the two branches of the beam-thermal DD fusion reactions, and fast ion Dα emission produced by beam ions. The instabilities driven by the beam are seen over a wide frequency range: i) fishbones at 10-50 kHz, ii) TAE at 50-150 kHz, Alfven cyclotron instabilities at 400 kHz-3.8 MHz. Special attention was paid on MAST to establishing the link to NSTX data on beam-driven “avalanches” consisting of several coupled TAEs with strong downward frequency sweep and higher amplitudes than un-coupled TAEs.Based on measurements from the neutron camera, as well as the FIDA and proton detector measurements, the effects of fast ion-driven instabilities on the beam profile are assessed, and modelling is performed with the HAGIS code. A search for plasma scenario minimising the effect of fast ion-driven instabilities on the beam radial profile was performed by scanning plasma density. Together, these studies aim at providing the data base to design experiments on MAST-Upgrade with its higher BT and off-axis beams, which will test extensively theories and models used for ITER and DEMO.
This work was part-funded by the RCUK Energy Programme and by EURATOM and carried out within the framework of European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission
| Country or International Organisation | UK |
|---|---|
| Paper Number | EX/P4-34 |
Primary author
Dr
Sergei Sharapov
(CCFE)
Co-authors
Dr
David Keeling
(CCFE)
Dr
Eric D. Fredrickson
(PPPL)
Dr
Geof Cunningham
(CCFE)
Dr
Iwona Klimek
(Uppsala University)
Dr
James Harrison
(CCFE)
Mr
James Oliver
(Bristol University)
Dr
Jon Hillesheim
(CCFE)
Dr
Ken McClements
(CCFE)
Dr
Marco Cecconello
(Uppsala University)
Dr
Mattew K. Lilley
(Imperial College, London)
Dr
Michael Fitzgerald
(CCFE)
Dr
Nizar Ben Ayed
(CCFE)
Dr
Owen Jones
(CCFE)
Dr
Ramona V. Perez
(Florida International University)
Dr
Rob Akers
(CCFE)
Dr
Robert Nyqvist
(Chalmers University of Technology)
Prof.
Werner U. Boeglin
(Florida International University)
