Upgraded bolometer system on JET for improved radiation measurements

Huber, A.; McCormick, K.; Andrew, P.; Beaumont, P.; Dalley, S.; Fink, J.; Fuchs, Julien; Fullard, K.; Fundamenski, W.; Ingesson, L. C.; Mast, F.; Jachmich, A.; Matthews, G. F.; Mertens, Philippe; Philipps, V.; Pitts, R.A.; Sanders, S.; Zeidner, W.; Contributors, Jet‐Efda

doi:10.1016/j.fusengdes.2007.03.027

Cited by 91 publications

(73 citation statements)

References 9 publications

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“…It is interesting to note that although the C 6+ content is similar in the two cases, the C 4+ concentration exhibits a much stronger increase with ICRF power in the N = 2 3 He heating case, suggesting that most of the radiation losses in these discharges come from the outer region of the plasma rather than from the plasma core. 2D bolometric tomography [29] confirmed this hypothesis and revealed that a significant part of the radiation observed in the 3 He heating discharges comes from the plasma periphery and from the divertor region.…”

Section: Impurity Generation and Performance Comparisonmentioning

confidence: 65%

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Lerche¹,

Eester²,

Johnson³

et al. 2012

Plasma Phys. Control. Fusion

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Two ion cyclotron range of frequencies (ICRF) heating schemes proposed for the half-field operation phase of ITER in hydrogen plasmas-fundamental H majority and second harmonic 3 He ICRF heating-were recently investigated in JET. Although the same magnetic field and RF frequencies (f ≈ 42 MHz and f ≈ 52 MHz, respectively) were used, the density and particularly the plasma temperature were lower than those expected in the initial phase of ITER. Unlike for the well-performing H minority heating scheme to be used in 4 He plasmas, modest heating efficiencies (η = P absorbed /P launched < 40%) with dominant electron heating were found in both H plasma scenarios studied, and enhanced plasma-wall interaction manifested by high radiation losses and relatively large impurity content in the plasma was observed. This effect was stronger in the 3 He ICRF heating case than in the H majority heating experiments and it was verified that concentrations as high as ∼20% are necessary to observe significant ion heating in this case. The RF acceleration of the heated ions was modest in both cases, although a small fraction of the 3 He ions reached about 260 keV in the second harmonic 3 He heating experiments when 11 Romanelli F et al 2010 Proc. 23rd IAEA Fusion Energy Conf. (Daejeon, Korea, 2010 5 MW of ICRF power was applied. Considerable RF acceleration of deuterium beam ions was also observed in some discharges of the 3 He heating experiments (where both the second and third harmonic ion cyclotron resonance layers of the D ions are inside the plasma) whilst it was practically absent in the majority hydrogen heating scenario. While hints of improved RF heating efficiency as a function of the plasma temperature and plasma dilution (with 4 He) were confirmed in the H majority case, the 3 He concentration was the main handle on the heating efficiency in the second harmonic 3 He heating scenario.

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Section: Impurity Generation and Performance Comparisonmentioning

confidence: 65%

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Lerche¹,

Eester²,

Johnson³

et al. 2012

Plasma Phys. Control. Fusion

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“…The D 2 gas fuelling into the inner divertor scrape-off layer has been progressively decreased from a fuelling rate of C gas = 10 22 molecules/s to C gas = 0 to produce a scan in ELM amplitude and frequency at high W plasma ($8 MJ). The JET bolometer camera system has recently been substantially upgraded, allowing significantly improved spatial and temporal resolution of the radiation distribution (Dr $ 8 cm in the divertor region, Dt $ 1 ms), particularly in the divertor region [2]. This allows a greatly improved tomographic reconstruction of the radiation pattern on a timescale of the order of the typical duration of a Type I ELM cycle ($1 ms).…”

Section: Experimental Set-upmentioning

confidence: 99%

Plasma radiation distribution and radiation loads onto the vessel during transient events in JET

Huber¹,

Pitts²,

Loarte³

et al. 2009

Journal of Nuclear Materials

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“…The tool was once developed for the measurement and assessment of the ITER bolometer diagnostic [7] and is based on work conducted at JET [12] [13]. Experience to analyse and evaluate the results were gained during the collimator development for ITER [14].…”

Section: Experimental Set-upmentioning

confidence: 99%

Automated in situ line of sight calibration of ASDEX Upgrade bolometers

Penzel

Meister

Bernert

et al. 2014

Fusion Engineering and Design

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The ITER Bolometer Robot Test Rig (IBOROB) is a robot-based diagnostic tool, which allows the measurement of the lines of sight (LOS) of the ITER bolometer prototypes. Up to now, it was only used as a LOS characterization device for the ITER collimator development. IBOROB was further developed and can now be operated in ASDEX Upgrade during a regular maintenance shutdown. At present, once a diagnostic like the bolometry is mounted inside the vessel, the actual LOS orientations are not measured, they are derived from CAD. The new procedure allows the fully automatic three-dimensional in situ measurement of bolometer LOS. The spatial distribution, the poloidal and toroidal alignment in the experiment coordinate system (CS), can be determined. The absolute accuracy, in reference to the tokamak CS, is provided by an additional calibration performed with a measurement arm by FARO Technologies Inc. Therefore, the amount of misalignment from the theoretical expectations can be quantified. In addition specific camera type dependencies such as internal camera reflections can be identified. Due to the high position accuracy of the robot, the LOS can be resolved with a spatial resolution of up to 0.1• . The method is explained in detail and results from two exemplary bolometer foil cameras obtained in a first set-up in ASDEX Upgrade are presented. The different steps and components needed to apply the measurements in the vessel are described with a focus on the constraints, e.g. geometrical, for an application of this method in a tokamak. Finally the consequences of the results are extrapolated to ITER and evaluated.

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Upgraded bolometer system on JET for improved radiation measurements

Cited by 91 publications

References 9 publications

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Plasma radiation distribution and radiation loads onto the vessel during transient events in JET

Automated in situ line of sight calibration of ASDEX Upgrade bolometers

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