Tracer-Encapsulated Solid Pellet (TESPEL) injection system for the TJ-II stellarator

Tamura, N.; McCarthy, K. J.; Hayashi, Hiromi; Combs, S. K.; Foust, C. R.; García, R.; Panadero, N.; Pawelec, E.; Sánchez, J.; Navarro, Moses; Soleto, A.

doi:10.1063/1.4962303

Cited by 12 publications

(17 citation statements)

References 9 publications

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“…A second impurity injection method, known as tracer-encapsulated solid pellet (TESPEL), has also been implemented. For this, a TESPEL injector has been piggybacked to the upstream end of the cryogenic pellet injector [43]. TESPELs are small spherical (300 μm diam.…”

Section: Jinst 16 C12026mentioning

confidence: 99%

Plasma diagnostic systems and methods used on the stellarator TJ-II

McCarthy¹

2021

J. Inst.

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The TJ-II is a heliac-type stellarator device with major radius of 1.5 m and averaged minor radius ⩽0.22 m that has been operated at CIEMAT, Madrid since 1998. Its full magnetic field is created by a system of poloidal, central, toroidal and vertical field coils, thus it possesses a fully 3-dimensional plasma structure and a bean-shaped plasma cross-section. Although this results in a complicated vacuum-vessel layout, it has excellent port access for diagnostics (96 portholes). During its initial operational phase, it was equipped with a limited set of essential diagnostics. Since then, a broad variety and large number of both passive and active diagnostics have been installed. The former include Hα monitors, light spectrometers, an electron cyclotron emission radiometer, X-ray filter monitors, neutral particle analysers, magnetic diagnostics, as well as cameras, among others, while the latter include various laser, atomic and ion beam based diagnostics, microwave probe beams, Langmuir probes plus impurity injection techniques. In this paper, after describing the TJ-II stellarator, its heating and fuelling systems, the diagnostic systems employed are outlined and discussed briefly here. Finally, results obtained with selected systems are highlighted.

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Section: Jinst 16 C12026mentioning

confidence: 99%

Plasma diagnostic systems and methods used on the stellarator TJ-II

McCarthy¹

2021

J. Inst.

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“…One such injection technique, a laser blow-off (LBO) [e.g., 1, 2], can inject the impurities repetitively into a single discharge, and then the impurity transport study can be performed efficiently by using the LBO [e.g., 3,4]. On the other hand, a tracer-encapsulated solid pellet (TESPEL) injection technique [5][6][7], which has been developed by our group, could only inject a single TESPEL into a typical plasma discharge (e.g., the typical duration of the LHD discharge ranges approximately from 3 seconds to 6 seconds), because the time required for the next TESPEL to be set at the injection axis is about 30 seconds by using the currently-used TESPEL holding disk. The TESPEL has the following advantages over the LBO from the viewpoint of the study of impurity transport in the core region of the confined plasma.…”

Section: Introductionmentioning

confidence: 99%

Development of a double-barreled Tracer Encapsulated Solid Pellet (TESPEL) injection system for LHD

Tamura¹,

Hayashi²,

Uejima³

et al. 2021

J. Inst.

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“…The TESPEL can release impurities at a well-localized radial position directly in the core plasma. Such a system was already deployed at LHD [8,9] and TJ-II [10]. Owing to its capability of containing multiple tracers inside the TESPEL, the system offers possibility of comparing the behaviour of various impurities exactly in the same plasma condition.…”

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confidence: 99%

Observation of the TESPEL-injected impurities behaviour by the PHA system at Wendelstein 7-X

Kubkowska¹,

Tamura

Chomiczewska³

et al. 2020

J. Inst.

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The Pulse Height Analysis (PHA) system at Wendelstein 7-X (W7-X) is a broad energy range spectrometer dedicated to the observation of impurity behaviour during the plasma discharges. The system measures spectra in the range between 0.5 and 20 keV, from integrated signals along three lines of sight that pass close to the plasma center. During the recent operational phase of W7-X, the TESPEL (Tracer-Encapsulated Solid PELlet) injector has been commissioned. By this injector, polystyrene pellets with a single tracer impurity as well as multiple tracer impurities have been injected into the W7-X plasmas. The multiple tracer impurities injection allows studying the behavior of various impurities in the same plasma condition. The time resolution of the PHA system in the order of 60-100 ms, is smaller than typical confinement times and sufficient to observe differences in temporal behaviour of injected impurities. The collected PHA spectra consist of Kα lines of vanadium, manganese and nickel in case of the triple tracers, and of iron or copper in case of the single tracer. The temporal evolution of these Kα lines has been obtained in various plasma conditions, which will be presented and discussed in this paper.

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Tracer-Encapsulated Solid Pellet (TESPEL) injection system for the TJ-II stellarator

Cited by 12 publications

References 9 publications

Plasma diagnostic systems and methods used on the stellarator TJ-II

Plasma diagnostic systems and methods used on the stellarator TJ-II

Development of a double-barreled Tracer Encapsulated Solid Pellet (TESPEL) injection system for LHD

Observation of the TESPEL-injected impurities behaviour by the PHA system at Wendelstein 7-X

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