Stabilization of sawteeth with third harmonic deuterium ICRF-accelerated beam in JET plasmas

Journal Article · Fri Jan 15 00:00:00 EST 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4939534· OSTI ID:22493815

Girardo, Jean-Baptiste ^[1]; Sharapov, Sergei; Fitzgerald, Michael; Hawkes, Nick; Kiptily, Vasily; Lupelli, Ivan ^[2]; Boom, Jurrian ^[3]; Dumont, Rémi; Garbet, Xavier; Sarazin, Yanick; Schneider, Mireille ^[4]; Eriksson, Jacob ^[5]; Mantsinen, Mervi ^[6]

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1. EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
2. CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
3. Max-Planck-Institut für Plasmaphysik, 85748 Garching (Germany)
4. CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)
5. Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala (Sweden)
6. Catalan Institution for Research and Advanced Studies, 08010 Barcelona (Spain)

Sawtooth stabilisation by fast ions is investigated in deuterium (D) and D-helium 3 (He3) plasmas of JET heated by deuterium Neutral Beam Injection combined in synergy with Ion Cyclotron Resonance Heating (ICRH) applied on-axis at 3rd beam cyclotron harmonic. A very significant increase in the sawtooth period is observed, caused by the ICRH-acceleration of the beam ions born at 100 keV to the MeV energy range. Four representative sawteeth from four different discharges are compared with Porcelli's model. In two discharges, the sawtooth crash appears to be triggered by core-localized Toroidal Alfvén Eigenmodes inside the q = 1 surface (also called “tornado” modes) which expel the fast ions from within the q = 1 surface, over time scales comparable with the sawtooth period. Two other discharges did not exhibit fast ion-driven instabilities in the plasma core, and no degradation of fast ion confinement was found in both modelling and direct measurements of fast ion profile with the neutron camera. The developed sawtooth scenario without fast ion-driven instabilities in the plasma core is of high interest for the burning plasmas. Possible causes of the sawtooth crashes on JET are discussed.

• OSTI ID: 22493815
• Journal Information: Physics of Plasmas, Vol. 23, Issue 1; Other Information: (c) 2016 EURATOM; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
BEAM INJECTION
DEUTERIUM
HELIUM 3
ICR HEATING
IONS
JET TOKAMAK
KEV RANGE 10-100
MEV RANGE
NEUTRON CAMERAS
PLASMA
PLASMA CONFINEMENT
PLASMA INSTABILITY
SAWTOOTH OSCILLATIONS
STABILIZATION
TOROIDAL CONFIGURATION