Articolo in rivista, 2018, ENG, 10.1088/1741-4326/aaa781

Density and magnetic fluctuations in type III-ELM pedestal evolution in JET: Experimental and numerical characterization

De Masi G.; Predebon I.; Spagnolo S.; Meneses L.; Delabie E.; Lupelli I.; Hillesheim J.C.; Maggi C.

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom; 1,2,3: Consorzio RFX, Corso Stati Uniti 4, 35127 Padova, Italy; 4: Instituto de Plasmas e Fusão Nuclear, Instituto Superior Tecnico, Universidade de Lisboa, Lisboa, Portugal; 5: Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169, United States of America; 6,7,8: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.

Density and magnetic fluctuation measurements in low-? type-III ELM discharges are obtained in the Joint European Torus (JET). They are observed during the inter-ELM pedestal evolution, after the LH transition phase, at about 60-70 kHz. Density fluctuations are measured with a correlation reflectometer system installed on the low-field side and they are localized at the pedestal top. Magnetic fluctuations with a spatial scale are measured through a high resolution coil array. The main features and the relations with local plasma parameters are presented. The nature of these fluctuations is discussed along with linear gyrokinetic simulations. Ion temperature gradient (ITG) modes are the dominant instabilities in the frequency range of interest. In terms of radial localization, typical oscillation frequency and qualitative relation with the possible linear drive, ITG modes are consistent with the experimental density fluctuations measurements. Micro-tearing modes (MTMs), found unstable with a lower growth rate, appear a possible explanation for magnetic fluctuations in terms of typical wavenumbers and direction of propagation.

Nuclear fusion 58 (4), pp. 046007-1–046007-11

Keywords

gyrokinetic simulations, ITG, JET, magnetic measurements, pedestal flcutuations, reflectometry, turbulence measurements

CNR authors

Predebon Italo

CNR institutes

IGI – Istituto gas ionizzati

ID: 387028

Year: 2018

Type: Articolo in rivista

Creation: 2018-05-04 14:18:28.000

Last update: 2020-04-07 12:32:31.000

CNR authors

External IDs

CNR OAI-PMH: oai:it.cnr:prodotti:387028

DOI: 10.1088/1741-4326/aaa781

Scopus: 2-s2.0-85044958991

ISI Web of Science (WOS): 000424504400007