Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET
- Westerhof, E.
- Sauter, O.
- Gondhalekar, A.
- Hellsten, T.
- Hender, T. C.
- Johnson, T.
- Lamalle, P.
- Maraschek, M. E.
- McClements, K. G.
- Nguyen, C. J.
- Pécquet, A. L.
- Podda, S.
- Mayoral, I. C.
- Rapp, J.
- Sharapov, S. E.
- Zabiego, M.
- Howell, D. F.
- Mantsinen, M. J.
- Nave, M. F. F.
- Alper, B.
- Angioni, C.
- Belo, P.
- Buttery, R. J.
DOIAbstract
A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, beta(Nonset), is increased. The scenario has been explored experimentally in the Joint European Torus (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilization, favouring the triggering of NTMs and reducing beta(Nonset), the present experiments show that by toroidally directed waves, ion cyclotron curren...
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