Detailed <i>in situ</i> laser calibration of the infrared imaging video bolometer for the JT-60U tokamak

Parchamy, Homaira; Peterson, B.J.; Konoshima, S.; Hayashi, Hiroshi; Seo, D. C.; Ashikawa, N.; Team, Jt

doi:10.1063/1.2336471

Cited by 20 publications

(15 citation statements)

References 5 publications

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“…The spatial resolution in the divertor at the poloidal cross-section is approximately 15 cm. A calibration technique has recently been developed for the IR camera and for one point on the foil to allow absolute measurements of radiated power [9]. Using these calibration coefficients and the bit noise of the IR camera, the noise equivalent power density at the foil of the IRVB is calculated as 350 lW/cm 2 from Eq.…”

Section: The Jt-60u Irvbmentioning

confidence: 99%

Observation of divertor and core radiation in JT-60U by means of bolometric imaging

Peterson¹,

Konoshima²,

Parchamy³

et al. 2007

Journal of Nuclear Materials

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Section: The Jt-60u Irvbmentioning

confidence: 99%

Observation of divertor and core radiation in JT-60U by means of bolometric imaging

Peterson¹,

Konoshima²,

Parchamy³

et al. 2007

Journal of Nuclear Materials

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“…This quantity represents the spatial maximum of the temperature change due to the foil heating by the laser. The temperature rise and decay are fit to a modified Gaussian [4] to find the rise and decay time contstants, respectively, which are averaged to give an effective thermal time constant, τ, in order to partially remove the effect of the IR radiation. If we neglect the blackbody radiation from the foil then τ ∝ 1/κ and ΔT ∝ 1/kt f and therefore the sensitivity can be written 035-2…”

Section: Experimental Techniquementioning

confidence: 99%

“…The InfraRed imaging Video Bolometer (IRVB) has been under development for application to a fusion reactor due to its durability vis-à-vis neutrons and gammas and its lack of in-vessel wires and the numerous vacuum feedthroughs which plague conventional resistive bolometers [2][3][4]. Also it provides an image of the radiation from the plasma which can be useful for steady-state reactor operation [5].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Au and Pt Foils for an Imaging Bolometer

Peterson

Drapiko

Seo

et al. 2010

Plasma and Fusion Research

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In the imaging bolometer a thin metal foil converts plasma radiated power to infrared radiation measured by an infrared camera. Calibration of the foil provides information on its sensitivity, which is helpful in selecting the best foil material. In this study thermal properties of submicron Au and Pt foils are investigated by heating the foils with a chopped HeNe laser beam (∼20 mW) and observing the temperature change, ΔT , and thermal time constant, τ, of the foil temperature. Assuming that the foil cooling is dominated by diffusion, we can compare the relative sensitivities of the foils by comparing the ratio of the thermal diffusivity to the thermal conductivity of the foil, κ/k, to the ratio ΔT/τ. The results indicate that Pt is more than 9 times more sensitive than Au even though standard thermal properties indicate that Au should be slightly (14%) more sensitive than Pt. This inconsistency indicates that the IR radiation is dominant over diffusion in the foil cooling. In that case the sensitivity should be evaluated by 1/k ∼ ΔT , which indicates that Pt is 8 times more sensitive than Au, while the ratio of thermal conductivities indicates that it should be only 4 times more sensitive.

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“…The collimation of the radiation through the aperture enables author's e-mail: peterson@LHD.nifs.ac.jp the 2D radiation profile on the foil to serve as an image of the plasma radiation. The calibration of the foil involves the determination of the 2D distribution of thermo-physical properties such as thermal diffusivity, thermal conductivity, foil thickness and blackbody emissivity [6]. In this paper two IRVBs which have been recently upgraded on LHD are described.…”

Section: Introductionmentioning

confidence: 99%

Upgrade of Imaging Bolometers on LHD

Peterson

Drapiko

Seo

et al. 2010

Plasma and Fusion Research

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Infrared Imaging Video Bolometers (IRVB) provide an image of the plasma radiation by using a thin metal foil to absorb the radiation, which is then imaged by an IR camera. In LHD IRVBs at Ports 6-T and 1-O have been upgraded. Both of the ∼ 1 micron × 70 mm × 90 mm gold foils have been replaced with ∼ 2.5 micron Pt foils of the same area for greater sensitivity (Pt vs Au) and absorption of higher energy photons estimated up to 8.2 keV. Also the IR cameras have been replaced; an FLIR/SC500 (∼ 100 mK, 60 fps, 320 × 240 pixels) IR camera at Port 1-O with a FLIR/Phoenix (∼ 16 mK, 345 fps, 320 × 256 pixels) IR camera at Port 10-O and an AGEMA/THV 900 LW (∼ 190 mK, 15 fps, 136 × 272 pixels)] with a FLIR SC-4000 (∼ 19 mK, 327 fps, 320 × 256 pixels) IR camera at port 6-T. In the current campaign these IRVBs will use 8 mm × 8 mm apertures resulting in 12 × 16 channels on the foil. The noise equivalent power density for these two new IRVBs ranges from ∼ 360 µW/cm 2 for 327 fps operation to 3.6 µW/cm 2 for 15 fps operation, which is over two orders of magnitude of improvement over the previous IRVB at Port 6-T.

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Detailed in situ laser calibration of the infrared imaging video bolometer for the JT-60U tokamak

Cited by 20 publications

References 5 publications

Observation of divertor and core radiation in JT-60U by means of bolometric imaging

Observation of divertor and core radiation in JT-60U by means of bolometric imaging

Comparison of Au and Pt Foils for an Imaging Bolometer

Upgrade of Imaging Bolometers on LHD

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