Design and Construction of the Tj-Ii Vacuum Vessel

Botija, J.; Blaumoser, M.; Bevilacqua, G.; Maso, S. Dal

doi:10.1016/b978-0-444-89995-8.50031-x

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…TJ-II presents specific PWI issues [15]: part of the vacuum chamber has a groove that surrounds the central conductor and acts as a helical limiter that intersects the magnetic field lines and receives the particle and heat parallel fluxes. The reason is that no natural ergodic zones appear outside the LCFS in TJ-II: the bean-shaped surfaces are extended as far as they are limited by the VV.…”

Section: The Plasma-wall Interaction In Tj-iimentioning

confidence: 99%

Flux-expansion divertor studies in TJ-II

Castejón¹,

Velasco²,

Löpez‐Fraguas³

et al. 2009

Nucl. Fusion

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The flux-expansion divertor concept is theoretically explored in TJ-II. This concept seems to be most suitable for this flexible stellarator in which the positions and the order of the resonances can be varied. As a first step, a family of configurations that exhibit flux expansion is identified. Then, a three-dimensional map of the collisional particle flux has been obtained for two different plasma regimes using the full-f Monte Carlo code ISDEP (Integrator of Stochastic Differential Equations in Plasmas), which computes the ion guiding-centre trajectories. The particle trajectories rather than the field lines must be considered since ion orbits can drift from the field lines in TJ-II and the plasma electric field and the collisionality must be considered in such calculations. We have checked that it is possible to strongly reduce the heat and particle fluxes by intercepting the trajectories at a given zone of the space. These calculations are done for thermal ions and for fast particles coming from the neutral beam injection heating. Future studies, possibly including the creation of an ergodic zone, will determine the best strategy for intercepting the trajectories.

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Section: The Plasma-wall Interaction In Tj-iimentioning

confidence: 99%

Flux-expansion divertor studies in TJ-II

Castejón¹,

Velasco²,

Löpez‐Fraguas³

et al. 2009

Nucl. Fusion

View full text Add to dashboard Cite

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Vacuum vessel, wall protection, pumping system and poloidal limiters of the Spanish stellarator TJ-II

Botija¹,

Barrera²,

Blaumoser³

et al.

15th IEEE/NPSS Symposium. Fusion Engineering

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TJ-II' i s a medium size stellarator under construction in Madrid, Spain, with an average major radius of &=1.5 m and a maximum minor radius a=0.2 m. The average toroidal field is 1 T. The pulse length varies from 0.2 s to 1 s and the duty cycle is 5 minutes. This device is capable to generate magnetic field configurations with rotational transform between 0.9 and 2.5, a shear between 1% and 10% and a magnetic well from 0 to 6%. Start of operation is expected in 1996. An RF heating power of 400 kW/53.2 GHz will be available in stage I of the experiment. Later in stage 11, 2 MW NBI power will be applied. In stage 111, 4 MW NBI power will be used.This paper reports on the engineering and design of the TJ-I1 in-vessel components as well as the pumping system. The vacuum vessel (VV) is an all-welded piece. Its groove is protected along the entire toroidal circumference against damage due to the bean-shaped plasma by 3 mm stainless steel sheets for the low and medium power operation (stage I and 11) and graphite tiles for the high power operation (stage 111). Furthermore, the VV is protected on the areas where the neutral beams deposit a residual shine-through heat flux. Four movable poloidal limiters will be used to limit the heat load on the groove area of the VV, especially during stage 111. The limiters will be movable to adjust them to the plasma geometry. The VV will be pumped through four symmetrically spaced bottom ports to a base pressure of mbar. Four identical and independent vacuum pumping subsystems will be used.

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Design and Construction of the Tj-Ii Vacuum Vessel

Cited by 2 publications

References 2 publications

Flux-expansion divertor studies in TJ-II

Flux-expansion divertor studies in TJ-II

Vacuum vessel, wall protection, pumping system and poloidal limiters of the Spanish stellarator TJ-II

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