The impact of poloidal asymmetries on tungsten transport in the core of JET H-mode plasmas

Recent progress in the understanding and prediction of the tungsten behaviour in the core of JET H-mode plasmas with ITER-like wall is presented. Particular emphasis is given to the impact of poloidal asymmetries of the impurity density. In particular, it is shown that the predicted reduction of temperature screening induced by the presence of low field side localization of the tungsten density produced by the centrifugal force is consistent with the observed tungsten behaviour in a JET discharge in H-mode baseline scenario. This provides first evidence of the role of poloidal asymmetries in reducing the strength of temperature screening. The main differences between plasma parameters in JET baseline and hybrid scenario discharges which affect the impact of poloidally asymmetric density on the tungsten radial transport are identified. This allows the conditions by which tungsten accumulation can be avoided to be more precisely defined.

[1]  P. Cochat,et al.  Et al , 2008, Archives de pediatrie : organe officiel de la Societe francaise de pediatrie.

[2]  S. Wong.  Transport of impure plasma with arbitrary toroidal rotation , 1987 .

[3]  J. Candy,et al.  Kinetic calculation of neoclassical transport including self-consistent electron and impurity dynamics , 2008 .

[4]  J. Rice,et al.  Parallel transport studies of high-Z impurities in the core of Alcator C-Mod plasmas , 2013 .

[5]  A. Hubbard,et al.  Poloidal variation of high-Z impurity density due to hydrogen minority ion cyclotron resonance heating on Alcator C-Mod , 2012 .

[6]  M. Mantsinen,et al.  Comparison of basis functions in soft x-ray tomography and observation of poloidal asymmetries in impurity density , 2000 .

[7]  P. C. de Vries,et al.  Role of sawtooth in avoiding impurity accumulation and maintaining good confinement in JET radiative mantle discharges , 2003 .

[8]  Tungsten Screening and Impurity Control in JET , 2013 .

[9]  A. ADoefaa,et al.  ? ? ? ? f ? ? ? ? ? , 2003 .

[10]  F. J. Casson,et al.  The nonlinear gyro-kinetic flux tube code GKW , 2009, Comput. Phys. Commun..

[11]  J. Candy,et al.  Pfirsch–Schlüter neoclassical heavy impurity transport in a rotating plasma , 2014 .

[12]  J. Contributors,et al.  Comparison of hybrid and baseline ELMy H-mode confinement in JET with the carbon wall , 2012 .

[13]  Y. Camenen,et al.  Gyrokinetic simulations including the centrifugal force in a rotating tokamak plasma , 2010 .

[14]  M. N. A. Beurskens,et al.  JET ITER-like wall—overview and experimental programme , 2011 .

[15]  F. Hinton,et al.  Neoclassical ion transport in rotating axisymmetric plasmas , 1985 .

[16]  P. T. Bonoli,et al.  Double transport barrier plasmas in Alcator C-Mod , 2002 .

[17]  S. Hirshman,et al.  Neoclassical transport of impurities in tokamak plasmas , 1981 .

[18]  A. Peeters,et al.  Direction of impurity pinch and auxiliary heating in tokamak plasmas. , 2006, Physical review letters.

[19]  C. Angioni,et al.  Neoclassical transport of heavy impurities with poloidally asymmetric density distribution in tokamaks , 2014 .

[20]  Jet Efda Contributors,et al.  First operation with the JET International Thermonuclear Experimental Reactor-like wall , 2013 .

[21]  Jet Efda Contributors,et al.  Observations on the W-transport in the core plasma of JET and ASDEX Upgrade , 2013 .

[22]  J. Contributors,et al.  Tungsten transport in JET H-mode plasmas in hybrid scenario, experimental observations and modelling , 2014 .

[23]  Jet Efda Contributors,et al.  High resolution Thomson scattering for Joint European Torus (JET) , 2004 .

[24]  F. J. Casson,et al.  Impact of the background toroidal rotation on particle and heat turbulent transport in tokamak plasmas , 2009 .

[25]  B. Alper,et al.  The JET soft x-ray diagnostic systems , 1997 .

[26]  J. Wesson.  Poloidal distribution of impurities in a rotating tokamak plasma , 1997 .

[27]  F. Casson,et al.  Analytic formulae for centrifugal effects on turbulent transport of trace impurities in tokamak plasmas , 2012 .

[28]  T. Fülöp,et al.  Effect of poloidal asymmetries on impurity peaking in tokamaks , 2012 .

[29]  J. Contributors,et al.  Theoretical description of heavy impurity transport and its application to the modelling of tungsten in JET and ASDEX upgrade , 2014, 1407.1191.

[30]  C. Bourdelle,et al.  Fluid simulations of turbulent impurity transport , 2007 .

[31]  Modelling the influence of temperature anisotropies on poloidal asymmetries of density in the core of rotating plasmas , 2014 .

[32]  M. Ottaviani,et al.  Effects of density asymmetries on heavy impurity transport in a rotating tokamak plasma , 1998 .

[33]  Nonlinear neoclassical transport in a rotating impure plasma with large gradients , 1999 .

[34]  M. Beurskens,et al.  Progress at JET in integrating ITER-relevant core and edge plasmas within the constraints of an ITER-like wall , 2015 .

[35]  Jeff M. Candy,et al.  Full linearized Fokker–Planck collisions in neoclassical transport simulations , 2011 .