The Toroidal Pump Limiter ALT-II in TEXTOR

Finken, K.H.; Reiter, D.; Denner, T.; Dippel, K.H.; Hobirk, J.; Mank, G.; Kever, H.; Wolf, G.H.; Noda, N.; Miyahara, Akira; Shoji, T.; Sato, K.; Akaishi, K.; Boedo, J.A.; Brooks, J.N.; Conn, R.W.; Corbett, W.J.; Doerner, R.; Goebel, Dan M.; Gray, D.S.; Hillis, D.L.; Hogan, J.; McGrath, R.T.; Matsunaga, Makoto; Moyer, R. A.; Nygren, R.E.; Watkins, J.G.

doi:10.13182/fst05-a694

Cited by 7 publications

(4 citation statements)

References 60 publications

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“…At the same time, the 3D magnetic topology in the plasma edge a mixture of closed field lines inside of the island separatrix and open field lines of various magnetic connection length connecting form the island Xpoint region to the wall [46,61,62]) is likely to alter the coupling to the ALTII limiter blades as exhaust device. For details of the ALTII layout and the pumping geometry, please see figure 2 in [43]. This is assessed using 20% increase of the toroidally averaged neutral pressure in the ALTII pump ducts is measured.…”

Section: Impact Of the Magnetic Island On The Neutral Pressure Distri...mentioning

confidence: 99%

“…In order to approach this, we report on comparative experi ments at TEXTOR and LHD. TEXTOR is a medium size limiter tokamak with a circular plasma shape featuring the Advanced Limiter Test II device (ALTII) [42,43]. Dedicated studies of its exhaust capacities have shown that it is effi cient to exhaust hydrogen and also helium from both cir cular Lmode as well as radiative improved mode (RI mode) TEXTOR plasmas [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of helium exhaust by resonant magnetic perturbation fields at LHD and TEXTOR

et al. 2016

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Sufficient exhaust of helium as a fusion born plasma impurity is a critical requirement for future burning plasmas. We demonstrate in this paper that resonant magnetic perturbation (RMP) fields can be used to actively improve helium exhaust features. We present results from the TEXTOR tokamak with a pumped limiter and from the LHD heliotron with the closed helical divertor. In both devices RMP fields are applied to generate a magnetic island located in the very plasma edge and this magnetic island has a noticeable impact on the helium exhaust. Also, the effect of the intrinsic stochasticity at the X-point of the LHD plasma on helium exhaust is investigated. Reduced helium fueling efficiency accompanied by enhanced outward transport is shown to facilitate enhanced helium exhaust from the system under RMP application. 3-D fluid plasma edge transport and kinetic neutral gas modeling with the EMC3-EIRENE code generally support these experimental findings.

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Section: Impact Of the Magnetic Island On The Neutral Pressure Distri...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancement of helium exhaust by resonant magnetic perturbation fields at LHD and TEXTOR

et al. 2016

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“…The position of the last closed flux surface (LCFS) is defined by the toroidal belt limiter ALT-II (Advanced Limiter Test II) [2]. ALT-II consists of 8 blades, each carrying 28 tiles ordered in two rows, with a total surface area of 3.4 m 2 .…”

Section: Introductionmentioning

confidence: 99%

Long-term erosion and deposition studies of the main graphite limiter in TEXTOR

Kreter¹,

Kirschner²,

Wienhold³

et al. 2007

Phys. Scr.

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Erosion and deposition behaviour of the TEXTOR main toroidal belt limiter ALT-II has been studied for two generations of limiter tiles with different surface shapes. Two specially prepared tiles with marker holes were subsequently exposed during experimental campaigns with a total plasma duration of > 7000 s and a surface averaged background ion fluence exceeding 2⋅10 25 m -2 . The tile surface relief was measured by optical profilometry and SIMS before and after the exposure. The highest surface erosion of > 10 μm on both tiles was observed in regions with an angle of incidence of the magnetic field α of > ~ 1°, whereas in the regions with α ~ 0.1° both net-erosion and net-deposition were observed depending on the tile shaping. The marker holes were always deposition dominated. Modelling by the ERO code explains qualitatively the surface erosion and deposition behaviour in terms of background flux dilution for shallow angles of incidence.

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“…The position of the last closed flux surface (LCFS) is defined by the toroidal belt limiter ALT-II (Advanced Limiter Test II) [12]. ALT-II consists of 8 blades, each carrying 28 tiles ordered in two poloidal rows, with a total surface area of 3.4 m 2 ( Fig.…”

mentioning

confidence: 99%

Long-term carbon transport and fuel retention in gaps of the main toroidal limiter in TEXTOR

Kreter

Wienhold

Esser

et al. 2013

Journal of Nuclear Materials

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The 1.1-1.5 mm wide gaps between tiles of the main toroidal belt limiter in TEXTOR were utilized to study the long-term impurity deposition and fuel retention in gaps. The tiles were exposed during a full tokamak campaign of 9365 s of plasma to various discharge conditions and wall conditioning, accumulating of up to 30 µm thick layers at the gap entrance. It was found that (i) gaps trap impurities twice as efficient as the top surface, (ii) the deposition in the toroidal gaps is twice as high as in the poloidal, (iii) carbon deposition decays with a fall-off length of about 0.7 mm towards the gap bottom, (iv) deposition on the bottom is significantly higher than on the adjacent side walls of gaps, (v) the amount of deuterium scales with the amount of carbon with D/C varying from 3% to 30% depending on the surface temperature.

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The Toroidal Pump Limiter ALT-II in TEXTOR

Cited by 7 publications

References 60 publications

Enhancement of helium exhaust by resonant magnetic perturbation fields at LHD and TEXTOR

Enhancement of helium exhaust by resonant magnetic perturbation fields at LHD and TEXTOR

Long-term erosion and deposition studies of the main graphite limiter in TEXTOR

Long-term carbon transport and fuel retention in gaps of the main toroidal limiter in TEXTOR

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