G. Pucella E. Alessi P. Buratti M. V. Falessi E. Giovannozzi F. Zonca M. Baruzzo C. D. Challis R. Dumont D. Frigione L. Garzotti J. Hobirk A. Kappatou D. L. Keeling D. King E. Lerche P. J. Lomas M. Maslov I. Nunes F. Rimini P. Siren C. Sozzi M. F. Stamp Z. Stancar D. Van Eester M. Zerbini
The experimental observation of multiple oscillations likely associated with beta-induced Alfven eigenmodes with toroidal mode number n = 1, 2 during strong tearing activity in JET plasmas is reported in this work. It is found the frequencies of these oscillations range from 5 kHz to 20 kHz, being consistent with the low-frequency beta-induc…
PreprintG. Pucella E. Giovannozzi P. Buratti E. Alessi F. Auriemma D. Brunetti P. J. Lomas S. Nowak C. Sozzi JET Contributors
In this work the mechanisms that can lead to disruptive MHD instabilities in the termination phase of plasma pulses on JET are investigated. It is shown that the broadening or the shrinking of the current density profile, as a consequence of a core hollowing or a edge cooling of the electron temperature profile, can lead to the destabilization o…
Preprint PublishedL. Piron T. C. Hender E. Joffrin F. Auriemma P. Buratti R. Paccagnella P. Zanca C. Challis S. Gerasimov R. B. Henriques L. Marrelli P. Lomas F. Rimini D. Terranova
The presence of Error Fields (EFs) in magnetic fusion devices can affect energy confinement and plasma stability by braking plasma rotation, by inducing fast particle losses and being amplified when exploring high-b regimes. The resulting EF Locked Modes (LMs) can be stabilized by NBI injection through the rotation shielding mechanism. However, …
Preprint PublishedS.N. Gerasimov G Artaserse P. Buratti I.S. Carvalho E. de la Luna T.C. Hender R.B. Henriques P.J. Lomas E. Matveeva S. Moradi L. Piron F.G. Rimini G. Szepesi L.E. Zakharov JET Contributors
An n = 1 locked, or slowly rotating, mode has been observed in most pulses prior to JET disruptions. However, a small fraction of non-disruptive pulses has a locked mode which eventually vanishes without disruption. Hence, on JET the locked mode amplitude is routinely used as an indicator of unhealthy plasma. There are two threshold levels…
Preprint PublishedSergei Gerasimov P. Abreu G Artaserse M. Baruzzo P. Buratti I.S. Carvalho I.H. Coffey E. de la Luna T.C. Hender R.B. Henriques R. Felton U. Kruezi P.J. Lomas P. McCullen M. Maslov E. Matveeva S. Moradi L. Piron F.G. Rimini W. Schippers G. Szepesi M. Tsalas L.E. Zakharov
The paper presents an analysis of disruptions occurring during JET-ILW plasma operations covering the period from the start of ILW (ITER-like wall) operation up to completion of JET operation in 2016. The total number of disruptions was 1951 including 466 with deliberately induced disruptions. The average disruption rate of unintended disruptions i…
Preprint PublishedC.D. Challis J. Garcia M. Beurskens P. Buratti E. Delabie P. Drewelow L. Frassinetti C. Giroud N. Hawkes J. Hobirk E. Joffrin D. Keeling D.B. King C.F. Maggi J. Mailloux C. Marchetto D. McDonald I. Nunes G. Pucella S. Saarelma J. Simps
The replacement of the JET carbon wall (C-wall) by a Be/W ITER-like wall (ILW) has affected the plasma energy confinement. To investigate this, experiments have been performed with both the C-wall and ILW to vary the heating power over a wide range for plasmas with different shapes. It was found that the power degradation of thermal energy confinem…
Preprint Published