TJ-II:Limiter

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TJ-II has two mobile limiters, located in sectors A3 and C3 (115.5º and 295.5º), with a toroidal separation of 180º. [1] The limiters are fitted with Langmuir probes and gas injection ports. [2] [3] [4] A biasing voltage can be applied. [5]

TJ-II Limiter and plasma
TJ-II Limiter: photograph taken from port B8TANG (the location of the fast camera)

Liquid Lithium limiters

Liquid Lithium Limiter with Capillary Porous System

On May 2012 the LLL was installed in sector A. [6] [7] [8] Experiments on D retention were performed at temperatures up to 400°C.[9] Also, biasing of the LLL respect to the plasma and respect to he C limiter in C3 were carried out.[10] Insertion of the LLL up to 3 cm into the edge was possible without any apparent damage. Biasing of the LLL to positive voltages led to improved energy and particle confinement in ECRH plasmas. [11] In 2014, a second LLL unit has been installed in C3 to replace the former C limiter.

References

  1. E. de la Cal et al, The diagnosed mobile limiters of the TJ-II stellarator for plasma boundary studies, J. Nucl. Mat. 266-269 (1999) 485
  2. E. de la Cal, B. Brañas, F.L. Tabarés, D. Tafalla, A.L. Fraguas, M.A. Pedrosa, V. Tribaldos, E. Ascasibar, J. Herranz, I. Pastor and TJ-II Team, Plasma boundary and SOL studies of ECH-plasmas in TJ-II stellarator with diagnosed mobile poloidal limiters, Journal of Nuclear Materials, 290-293 (2001) 579-583
  3. I. García-Cortés et al, Fuelling efficiency of hydrocarbons in TJ-II plasmas, J. Nucl. Mat. 337-339 (2005) 441-445
  4. E. de la Cal et al, Hydrogen recycling and puffing at a poloidal limiter of TJ-II, J. Nucl. Mat. 363-365 (2007) 764-769
  5. C. Hidalgo et al, Improved confinement regimes induced by limiter biasing in the TJ-II stellarator, Plasma Phys. Control. Fusion 46 (2004) 287-297
  6. A.V. Vertkov, I.E. Lyublinski, F. Tabares, E. Ascasibar, Development of Liquid Lithium Limiter for Stellarator TJ-II, 23rd IAEA Fusion Energy Conference, Daejon, Korea (2010) FTP/P1-34
  7. I.E. Lyublinski, A.V. Vertkov, et al., Development and experimental study of Lithium based plasma facing elements for fusion reactor application, 23rd IAEA Fusion Energy Conference, Daejon, Korea (2010) FTP/3-6Rb
  8. A.V. Vertkov, F. L. Tabarés et al. Fus. Eng. and Design 87 (2012) 1755 - 1759
  9. F.L. Tabarés et al. Studies of Plasma-Lithium Interactions in TJ-II. IAEA 2012. P5/36
  10. E. Oyarzabal et al. Proc 17th ISHW Padova, Sept 2013.
  11. F.L. Tabarés et al. Proc 3rd ISLA Conference. Frascati, Oct 2013