Impact of divertor geometry on H-mode confinement in the JET metallic wall

Recent experiments with the ITER-like wall have demonstrated that changes in divertor strike point position are correlated with strong modification of the global energy confinement. The impact on energy confinement is observable both on the pedestal confinement and core normalised gradients. The corner configuration shows an increased core density gradient length and ion pressure indicating a better ion confinement. The study of neutral re-circulation indicates the neutral pressure in the main chamber varies inversely with the energy confinement and a correlation between the pedestal total pressure and the neutral pressure in the main chamber can be established. It does not appear that charge exchange losses nor momentum losses could explain this effect, but it may be that changes in edge electric potential are playing a role at the plasma edge. This study emphasizes the importance of the scrape-off layer (SOL) conditions on the pedestal and core confinement.

[1]  J. Contributors,et al.  The role of MHD in causing impurity peaking in JET hybrid plasmas , 2015, 1510.03228.

[2]  A. Sips,et al.  Pedestal confinement and stability in JET-ILW ELMy H-modes , 2015 .

[3]  Jet Efda Contributors,et al.  Investigation of the influence of divertor recycling on global plasma confinement in JET ITER-like wall , 2015 .

[4]  S. Brezinsek,et al.  Plasma-surface interaction in the Be/W environment: Conclusions drawn from the JET-ILW for ITER , 2015 .

[5]  G. Pucella,et al.  Improved confinement in JET high β plasmas with an ITER-like wall , 2015, 1501.03929.

[6]  Jet Efda Contributors,et al.  Global and pedestal confinement in JET with a Be/W metallic wall , 2014 .

[7]  R. Neu,et al.  Experiences With Tungsten Plasma Facing Components in ASDEX Upgrade and JET , 2014, IEEE Transactions on Plasma Science.

[8]  Y Liu,et al.  Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall , 2013, 1310.8433.

[9]  M. Beurskens,et al.  Impact of carbon and tungsten as divertor materials on the scrape-off layer conditions in JET , 2013 .

[10]  J. Bucalossi,et al.  Near wall plasma simulation using penalization technique with the transport code SolEdge2D-Eirene , 2013 .

[11]  T. Tala,et al.  Momentum losses by charge exchange with neutral particles in H-mode discharges at JET , 2011 .

[12]  J. Contributors,et al.  Density profile peaking in JET H-mode plasmas: experiments versus linear gyrokinetic predictions , 2009 .

[13]  J. Contributors,et al.  Accuracy of EFIT equilibrium reconstruction with internal diagnostic information at JET. , 2008, The Review of scientific instruments.

[14]  J. Contributors,et al.  Pedestal and ELM response to impurity seeding in JET advanced scenario plasmas , 2008 .

[15]  V. Parail,et al.  Edge transport barrier formation studies on JET with the JETTO code , 2008 .

[16]  M. Kempenaars,et al.  Predictive modelling of the impact of argon injection on H-mode plasmas in JET with the RITM code , 2004 .

[17]  R. Neu,et al.  Edge transport and its interconnection with main chamber recycling in ASDEX Upgrade , 2003 .

[18]  B. Schweer,et al.  Evidence for reduction of the toroidal ITG instability in the transition from saturated to improved Ohmic confinement in the tokamak TEXTOR , 2003 .

[19]  F. Milani,et al.  Scaling of the pedestal density in type-I ELMy H-mode discharges and the impact of upper and lower triangularity in JET and ASDEX Upgrade , 2002 .

[20]  H. Wilson,et al.  Numerical studies of edge localized instabilities in tokamaks , 2002 .

[21]  T. Fülöp,et al.  Effect of neutral atoms on tokamak edge plasmas , 2001 .

[22]  E. Pohn,et al.  Study of the formation of a charge separation at a plasma edge. Part II. Comparison between three different interpolation methods for the solution of the kinetic Vlasov equation , 2001 .

[23]  A. Loarte.  Effects of divertor geometry on tokamak plasmas , 2001 .

[24]  J. Connor,et al.  Neutral particle and radiation effects on Pfirsch–Schlüter fluxes near the edge , 1998 .

[25]  Detlev Reiter,et al.  Progress in two-dimensional plasma edge modelling , 1992 .

[26]  H. Matsumoto,et al.  H-mode and recycling control in JFT-2M , 1990 .

[27]  R. Goldston,et al.  New techniques for calculating heat and particle source rates due to neutral beam injection in axisymmetric tokamaks , 1981 .

[28]  I. Lupelli,et al.  Dimensionless scalings of confinement, heat transport and pedestal stability in JET-ILW and comparison with JET-C , 2016 .

[29]  C. Giroud,et al.  Plasma confinement at JET , 2015 .

[30]  G. Pucella,et al.  Improved Confinement in JET High Beta Plasmas with an ITER-Like Wall , 2015 .

[31]  Jet Efda Contributors,et al.  First scenario development with the JET new ITER-like wall , 2013 .

[32]  Eric Gauthier,et al.  Studies in JET divertors of varied geometry. I: Non-seeded plasma operation , 1999 .