Wall conditioning with impurity pellet injection on TFTR

Snipes, J. A.; Marmar, E.; Terry, J. L.; Bell, M.G.; Budny, R.; Hill, K. W.; Jassby, D.L.; Mansfield, D. K.; Meade, D. M.; Park, H.K.; Strachan, J.D.; Stratton, B. C.; Synakowski, E. J.; Taylor, G.; Ruzic, D. N.; Shaheen, Mohammed

doi:10.1016/s0022-3115(06)80123-6

Cited by 79 publications

(46 citation statements)

References 7 publications

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“…Recently, there is growing use of lithium coatings in particular to control edge recycling and improve energy confinement [2][3][4][5][6] . The basic concept is to coat the plasma-facing components (PFC) with tens of atomic monolayers of low-Z elements, reducing higher-Z impurity generation and influx, which detracts from plasma performance.…”

Section: Body Textmentioning

confidence: 99%

Continuous Improvement of H-Mode Discharge Performance with Progressively Increasing Lithium Coatings in the National Spherical Torus Experiment

et al. 2011

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Section: Body Textmentioning

confidence: 99%

Continuous Improvement of H-Mode Discharge Performance with Progressively Increasing Lithium Coatings in the National Spherical Torus Experiment

et al. 2011

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“…This deposition was carried out in earlier experiments by the injection and ablation of a few small (3 mg each) Li pellets [3,4,5,6]. In order to improve plasma performance during NBI, Li pellets were typically injected into the Ohmic phase of discharges and the ablated Li was allowed to 3 condense out of the plasma column and onto the limiter surface before the application of auxiliary heating.…”

Section: Introductionmentioning

confidence: 99%

Observations concerning the injection of a lithium aerosol into the edge of TFTR discharges

et al. 2001

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A new method of actively modifying the plasma-wall interaction was tested on the Tokamak Fusion Test Reactor. A laser was used to introduce a directed lithium aerosol into the discharge scrape-off layer. The lithium introduced in this fashion ablated a n d migrated preferentially to the limiter contact points. This allowed the plasma-wall interaction to be influenced in situ and in real t i m e by external means. Significant improvement in energy confinement and fusion neutron production rate as well as a reduction in t h e plasma Z eff have been documented in a neutral-beam-heated plasma. The introduction of a metallic aerosol into the plasma e d g e increased the internal inductance of the plasma column and also resulted in prompt heating of core electrons in Ohmic plasmas. Preliminary evidence also suggests that the introduction of a n aerosol leads to both edge poloidal velocity shear and edge electric field shear. . I n t r o d u c t i o nIt has been well documented that the fusion performance of discharges in the Tokamak Fusion Test Reactor (TFTR) was strongly dependent on the physical and chemical condition of the graphite surface forming its limiter [1,2]. In particular, the highperformance supershot mode of operation was attainable at high currents (>2.0 MA) only when the graphite inner wall had previously been "scoured" by repeated discharges heated by high-power neutral beam injection (NBI) in order to render the limiter surface free of loosely-bound carbon and loosely-adsorbed hydrogenic material. At the end of a series of such pre-conditioning discharges, plasma fueling from the limiter typically reached a minimum.Moreover, only when this low-recycling condition had been attained did high levels of fusion performance become accessible.It has also been well documented that dramatic improvements in supershot fusion performance were attainable by the deposition of elemental lithium (Li) onto the limiter surface once it had been brought into the low-recycling condition. This deposition was carried out in earlier experiments by the injection and ablation of a few small (3 mg each) Li pellets [3,4,5,6]. In order to improve plasma performance during NBI, Li pellets were typically injected into the Ohmic phase of discharges and the ablated Li was allowed to 3 condense out of the plasma column and onto the limiter surface before the application of auxiliary heating. While the use of Li pellets did improve plasma performance, the technique was, nonetheless, highly perturbing. In order to reduce the perturbation to the plasma, brief but successful experiments with a Li effusion oven were also carried out on TFTR and are described elsewhere [7,8].While the use of an oven did result in an increase in the amount of Li deposited onto the inner wall as compared to pellet injection, deposition could only take place between discharges and not during the discharge of interest.In this work, an alternate wall-conditioning technique is described in which Li was injected into the scrape-off layer (SOL), during pl...

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“…In fact, lithium can actually improve tokamak cleanliness, and has been used on the graphite first walled TFTR [20] and DIII-D [21] tokamaks to reduce carbon and oxygen impurity concentrations.…”

Section: Pellets: Size Composition and Fabricationmentioning

confidence: 99%

Lithium pellet injection experiments on the Alcator C-Mod tokamak

Garnier

1996

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Wall conditioning with impurity pellet injection on TFTR

Cited by 79 publications

References 7 publications

Continuous Improvement of H-Mode Discharge Performance with Progressively Increasing Lithium Coatings in the National Spherical Torus Experiment

Continuous Improvement of H-Mode Discharge Performance with Progressively Increasing Lithium Coatings in the National Spherical Torus Experiment

Observations concerning the injection of a lithium aerosol into the edge of TFTR discharges

Lithium pellet injection experiments on the Alcator C-Mod tokamak

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