TJ-II:Vacuum system

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An octant of the TJ-II vacuum vessel with its many ports. On the right, part of the groove is visible.
Interior view of the TJ-II vacuum vessel during assembly. The helical coil, fitting in the groove, is visible on the left.

Vacuum vessel

The all-metal TJ-II vacuum vessel has a helical geometry and has 96 ports. [1] [2] The vacuum vessel is made of non-magnetic steel (304 LN) with a thickness of 10 mm. The CC/HX coil is outside of the vacuum vessel thanks to a helical groove built into the vessel. This groove has a wall thickness of 7 mm for clearance reasons. The groove is protected along the entire toroidal circumference against damage due to the bean-shaped plasma by 3 mm stainless steel sheets for low and medium power operation and graphite tiles for high power operation. Furthermore, the vacuum vessel is protected on the areas where the neutral beams deposit a residual shine-through heat flux.

Vacuum system

The vacuum vessel is pumped through four symmetrically spaced bottom ports to a base pressure of 10-8 mbar. Four identical and independent vacuum pumping subsystems are used. [3] [4] [5]

See also

A computer model of the TJ-II vacuum vessel. It can be seen how the plasma hugs the groove of the vessel.

References

  1. M. Baldarelli, A, Cecchini, M, Cucchiaro, et al., Vacuum vessel design for the TJ-II Heliac, Proc. 16th Symposium on Fusion Technology, London, U.K., 3–7 September 1990, 453
  2. J. Botija and M. Blaumoser, Vacuum vessel design for the TJ-II device, 14th IEEE/NPSS Symposium on Fusion Engineering 2 (1991) 992-995
  3. J. Botija et al, Vacuum vessel, wall protection, pumping system and poloidal limiters of the Spanish stellarator TJ-II, 15th IEEE/NPSS Symposium on Fusion Engineering 1 (1993) 529-532
  4. F. Tabarés, The vacuum system of the TJ-II stellarator, Vacuum 45, Issues 10-11 (1994) 1059-1061
  5. R. Carrasco, Hybrid baking system for the vacuum vessel of the Spanish stellarator TJ-II, Proc. 18th Symposium on Fusion Engineering (1999) 231-234