C.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 PublishedS. Saarelma A. Järvinen M. Beurskens C. Challis L. Frassinetti C. Giroud M. Groth M. Leyland C. Maggi J. Simpson JET Contributors
The H-mode pedestal plays an important role in determining global confinement in tokamaks. In high triangularity H-mode experiments in Joint European Torus with the ITER-like wall (JET-ILW), significantly higher pedestal temperature and global confinement have been achieved with nitrogen seeding. The experimentally observed increase in pedestal hei…
Preprint PublishedS. Menmuir C. Giroud T. M. Biewer I. H. Coffey E. Delabie N. C. Hawkes M. Sertoli JET EFDA Contributors
Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06nm and demonstrates the need to revise the core charge e…
PublishedS. Grünhagen Romanelli S. Brezinsek B. Butler J.P. Coad A. Drenik C. Giroud S. Jachmich T. Keenan U. Kruezi M. Mozetic M. Oberkofler A. Parracho M. Romanelli R. Smith JET EFDA Contributors
Analytical results of a complete JET cryopump regeneration, including the nitrogen panel, follow- ing the first ITER-Like Wall campaign are presented along with the in-situ analyses of residual gas. H/D mixtures and impurities such as nitrogen and neon were injected during plasma operation in the vessel to study radiation cooling in the scrape-off-…
PublishedG.P. Maddison C. Giroud B. Alper Et.Al.
The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between Type I H-mode characteristics in each design by examining respective scans over deuterium fuelling and impurity seeding, required to ameliorate exhaust…
PublishedM-L. Mayoral V. Bobkov A. Czarnecka I. Day A. Ekedahl P. Jacquet M. Goniche R. King K. Kirov E. Lerche J. Mailloux D. Van Eester O. Asunta C. Challis D. Ciric J.W. Coenen L. Colas C. Giroud M. Graham I. Jenkins E. Joffrin T. Jones D.
The major aspects linked to the use of the JET auxiliary heating systems: NBI, ICRF and LHCD, in the new JET ITER-like wall (JET-ILW) are presented. We show that although there were issues related to the operation of each system, efficient and safe plasma heating was obtained with room for higher power. For the NBI up to 25.7MW was safely injected;…
PublishedC. Giroud G.P. Maddison S. Jachmich F. Rimini M. Beurskens I. Balboa S. Brezinsek R. Coelho J.W.Coenen Et Al
This paper reports the impact on confinement and power load of the high-shape 2.5MA ELMy H-mode scenario at JET of a change from an all carbon plasma facing components to an all metal wall. In preparation to this change, systematic studies of power load reduction and impact on confinement as a result of fuelling in combination with nitrogen seeding…
PublishedF. I. Parra M. F. F. Nave A. A. Schekochihin C. Giroud J. S. De Grassie J. H. F. Severo P. De Vries K.-D. Zastrow
Using theoretical arguments, a simple scaling law for the size of the intrinsic rotation observed in tokamaks in the absence of a momentum injection is found: The velocity generated in the core of a tokamak must be proportional to the ion temperature difference in the core divided by the plasma current, independent of the size of the device. The co…
PublishedP. Mantica C. Angioni C. Challis G. Colyer L. Frassinetti N. Hawkes T. Johnson M. Tsalas P. C. Devries J. Weiland B. Baiocchi M. N. A. Beurskens A. C. A. Figueiredo C. Giroud J. Hobirk E. Joffrin E. Lerche V. Naulin A. G. Peeters A. Sal
New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. [ Phys. Rev. Lett. 102, 175002 (2009) ] results from the combined effect of high rotational shear and low magnetic shear. The observations have important implications for the understanding of improved ion core con…
PublishedVolker Naulin Jens Juul Rasmussen Clemente Angioni Carine Giroud Marco Valisa Maria Ester Puiatti L. Carraro
Impurity transport is an important topic for ITER as impurity density in tlie core has to stay below a relative concentration of 5 x 10~^ [1] to reach ignition conditions. The reasons for that is mainly impurity radiation leading to cooling. In the edge region on the other hand site, higher impurity densities, going along with radiation energy loss…
Published