Implementation of an in-vessel calibration light source for JET

Biewer, T. M.; Belcher, C. Davis; Hassall, I.; Hillis, D.L.; Kaveney, G.; Scharpf, Dan; Stamp, M.; Stunell, C.; Zastrow, K.‐D.; Contributors, Jet‐Efda

doi:10.1063/1.4729502

Cited by 12 publications

(6 citation statements)

References 1 publication

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“…The in-vessel calibration light source (ICLS) with a 4 in. diameter exit port and four lamps, 3 developed at Oak Ridge National Laboratory, has been positioned by RHA inside the JET vacuum vessel. L λ at these wavelengths, 980 nm and 1016 nm, correspond to the brightness temperatures, T br , of 975…”

Section: Calibration Of Protection Camerasmentioning

confidence: 99%

In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

Huber

Kinna

et al. 2016

Review of Scientific Instruments

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The in situ absolute calibration of the JET real-time protection imaging system has been performed for the first time by means of radiometric light source placed inside the JET vessel and operated by remote handling. High accuracy of the calibration is confirmed by cross-validation of the near infrared (NIR) cameras against each other, with thermal IR cameras, and with the beryllium evaporator, which lead to successful protection of the JET first wall during the last campaign. The operation temperature ranges of NIR protection cameras for the materials used on JET are Be 650-1600• C, W coating 600-1320• C, and W 650-1500

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Section: Calibration Of Protection Camerasmentioning

confidence: 99%

In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

Huber

Kinna

et al. 2016

Review of Scientific Instruments

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“…The JET edge CXRS diagnostic has been refurbished prior to the ILW experimental campaign, leading to profile data with improved time (10 ms) and spatial (~ 1.5 cm) resolution. In addition, the entire optical path of the diagnostic could be absolutely calibrated for the first time by means of in-vessel calibrations, which in JET can only be achieved with remote handling, as described in [32]. This technique has enabled improved accuracy in the edge impurity density measurements compared to the past.…”

Section: Local Analysis: Edge Radial Electric Field At the L-h Transimentioning

confidence: 99%

L–H power threshold studies in JET with Be/W and C wall

Delabie²,

et al. 2014

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A comparison of the L–H power threshold (Pthr) in JET with all carbon, JET-C, and beryllium/tungsten wall (the ITER-like choice), JET-ILW, has been carried out in experiments with slow input power ramps and matched plasma shapes, divertor configuration and IP/BT pairs. The low density dependence of the L–H power threshold, namely an increase below a minimum density ne,min, which was first observed in JET with the MkII-GB divertor and C wall and subsequently not observed with the current MkII-HD geometry, is observed again with JET-ILW. At plasma densities above ne,min, Pthr is reduced by ∼30%, and by ∼40% when the radiation from the bulk plasma is subtracted (Psep), with JET-ILW compared to JET-C. At the L–H transition the electron temperature at the edge, where the pedestal later develops, is also lower with JET-ILW, for a given edge density. With JET-ILW the minimum density is found to increase roughly linearly with magnetic field, , while the power threshold at the minimum density scales as . The H-mode power threshold in JET-ILW is found to be sensitive both to variations in main plasma shape (Psep decreases with increasing lower triangularity and increases with upper triangularity) and in divertor configuration. When the data are recast in terms of Psep and Zeff or subdivertor neutral pressure a linear correlation is found, pointing to a possible role of Zeff and/or subdivertor neutral pressure in the L–H transition physics. Depending on the chosen divertor configuration, Pthr can be up to a factor of two lower than the ITPA scaling law for densities above ne,min. A shallow edge radial electric field well is observed at the L–H transition. The edge impurity ion poloidal velocity remains low, close to its L-mode values, ⩽5 km s−1 ± 2–3 km s−1, at the L–H transition and throughout the H-mode phase, with no measureable increase within the experimental uncertainties. The edge toroidal rotation profile does not contribute to the depth of the negative Er well and thus may not be correlated with the formation of the edge transport barrier in JET.

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“…D-T operation at JET will cause failure of camera electronics within the Torus hall due to significant increase of the hard radiation level (neutrons/gammas). To provide the reliable wall protection needed during the coming D-T campaign, two camera systems, equipped with new optical relays to take the images and the cameras outside of the biological shield, have been installed on JET-ILW and calibrated with an in-vessel calibration light source [12,13]. The optical design concept of both systems with wide angle view as well as the divertor view is based on reflective optics, mainly to be able to sustain high neutron radiation.…”

Section: Future Development Of the Jet Real Time First Wall Protectionmentioning

confidence: 99%

The software and hardware architecture of the real-time protection of in-vessel components in JET-ILW

Huber

Kinna

et al. 2019

Nucl. Fusion

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For the first time, the JET operation in deuterium-tritium (D-T) plasma, which is scheduled to take place on JET in 2020, will be performed in the ITER mix of plasma-facing component materials. In view of the preparation of the DT campaign (DTE2), several aspects of the plasma operation require significant improvements, such as a real-time protection of the first wall. The risk of damaging the metallic PFCs caused by beryllium melting or cracking of tungsten owing to thermal fatigue required a new reliable D-T compatible active protection system. Therefore, the future development of the JET real time first wall protection is focused on the D-T campaign and the ITER relevant conditions which may cause failure of camera electronics within the Torus hall. In addition to the technological aspect, the intensive preparation of the diverse software tools and real time algorithms for hot spot detection as well as alarm handling strategy required for the wall protection is in progress.This contribution describes the improved design, implementation, and operation of the near infrared (NIR) imaging diagnostic system of the JET-ILW plasma experiment and its integration into the existing JET protection architecture. To provide the reliable wall protection during the DTE2, two more sensitive logarithmic NIR camera systems equipped with new optical relays to take images and cameras outside of the biological shield have been installed on JET-ILW and calibrated with an in-vessel calibration light source (ICLS). Additionally, post-pulse data visualization and advanced analysis of all types of imaging data is provided by the new software framework JUVIL (JET users video imaging library). The formation of hot spots is recognized as a significant threat due to rapid surface temperature rise. Because it could trigger the protection system to stop a pulse, it is important to identify the mechanisms and conditions responsible for the formation of such hot spots. To address this issue the new software tool 'Hotspot Editor' has been developed.

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Implementation of an in-vessel calibration light source for JET

Cited by 12 publications

References 1 publication

In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall

L–H power threshold studies in JET with Be/W and C wall

The software and hardware architecture of the real-time protection of in-vessel components in JET-ILW

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