Integration of a radiative divertor for heat load control into JET high triangularity ELMy H-mode plasmas

Experiments on JET with a carbon-fibre composite wall have explored the reduction of steady-state power load in an ELMy H-mode scenario at high Greenwald fraction similar to 0.8, constant power and close to the L to H transition. This paper reports a systematic study of power load reduction due to the effect of fuelling in combination with seeding over a wide range of pedestal density ((4-8) x 10(19) m(-3)) with detailed documentation of divertor, pedestal and main plasma conditions, as well as a comparative study of two extrinsic impurity nitrogen and neon. It also reports the impact of steady-state power load reduction on the overall plasma behaviour, as well as possible control parameters to increase fuel purity. Conditions from attached to fully detached divertor were obtained during this study. These experiments provide reference plasmas for comparison with a future JET Be first wall and an all W divertor where the power load reduction is mandatory for operation.

[1]  T. Petrie,et al.  Impurity behaviour under puff-and-pump radiating divertor conditions , 2009 .

[2]  J. Stober,et al.  Confinement of 'improved H-modes' in the all-tungsten ASDEX Upgrade with nitrogen seeding , 2011 .

[3]  O. Sauter,et al.  Hybrid H-mode scenario with nitrogen seeding and type III ELMs in JET , 2008 .

[4]  T. Osborne,et al.  Spatial resolution of the JET Thomson scattering system. , 2012, The Review of scientific instruments.

[5]  Kiyoshi Itami,et al.  Investigations of impurity seeding and radiation control for long-pulse and high-density H-mode plasmas in JT-60U , 2009 .

[6]  J. Contributors,et al.  Pedestal and scrape-off layer dynamics in ELMy H-mode plasmas in JET , 2009 .

[7]  S. J. Wukitch,et al.  High confinement/high radiated power H-mode experiments in Alcator C-Mod and consequences for International Thermonuclear Experimental Reactor (ITER) QDT = 10 operationa) , 2011 .

[8]  H. Koslowski,et al.  MHD stability analysis of small ELM regimes in JET , 2009 .

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

[10]  Jet Efda Contributors,et al.  H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET , 2011 .

[11]  Y. Kamada,et al.  Pedestal stability comparison and ITER pedestal prediction , 2009 .

[12]  A. Loarte,et al.  Analysis of performance of the optimized divertor in ITER , 2009 .

[13]  M. Beurskens,et al.  Moderation of divertor heat loads by fuelling and impurity seeding in well-confined ELMy H-mode plasmas on JET , 2011 .