TJ-II:Vacuum system
Vacuum vessel
The all-metal TJ-II vacuum vessel has a helical geometry and has 96 ports. 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. [1] [2]