Chapter 7: Radio-frequency wave physics in the FTU

G. Granucci, A. Airoldi, E. Barbato, A. Bruschi, A. Cardinali, C. Castaldo, R. Cesario, S. Cirant, B. Esposito, D. Farina, F. Gandini, G. Giruzzi, C. Gormezano, M. Leigheb, M. Marinucci, F. Mirizzi, S. Nowak, L. Panaccione, V. Pericoli-Ridolfini, S. PoddaG. Ramponi, G.L. Ravera, A.N. Saveliev, A. Simonetto, C. Sozzi, A.A. Tuccillo, F. Zonca

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Abstract

This chapter reports the main physics results obtained with three radio-frequency-injection systems. The frequency of 8 GHz for the lower hybrid (LH) current drive (CD) (LHCD) system was chosen to explore CD at high density: full CD has been demonstrated for central densities up to 1.4 × 1020m-3at 0.5 MA with an applied power up to 2.0 MW. The Frascati Tokamak Upgrade (FTU) database shows CD efficiencies from 0.1 to 0.3 × 1020AW-1m-2. In combined experiments with electron cyclotron (EC) waves (140 GHz, up to 1.2 MW), a suprathermal absorption by the fast electron tail generated by LHCD has been observed in both downshifted and up-shifted interaction regimes, with the resulting electron cyclotron current drive (ECCD) ranging from 20 to 100 kA, depending on experimental conditions. With pure EC resonance heating, the narrowness of the radial power deposition profile has been exploited, resulting in strong local electron heating. Results in high-density regimes are also presented. The third system (433 MHz, 0.5 MW) is the first to test ion Bernstein wave (IBW) coupling with a waveguide antenna. The experiment operates at high frequency, avoiding the occurrence of nonlinear phenomena at the edge. Improved confinement regimes resulting in a central peaking of the pressure profiles have been achieved with PIBWup to 0.4 MW. Modeling and experimental results are summarized.
Original languageEnglish
Pages (from-to)387 - 401
Number of pages15
JournalFusion Science and Technology
Volume45
Issue number3
DOIs
Publication statusPublished - 2004
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Granucci, G., Airoldi, A., Barbato, E., Bruschi, A., Cardinali, A., Castaldo, C., ... Zonca, F. (2004). Chapter 7: Radio-frequency wave physics in the FTU. Fusion Science and Technology, 45(3), 387 - 401. https://doi.org/10.13182/FST04-A521