Speaker
Scott Alan Silburn
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1008.pdf
Development of webcam-based near-infrared thermography in support of
high temperature heat pipe experiments on Magnum PSI
S. A. Silburn1, G. F. Matthews1, T. W. Morgan2, R. E. Nygren3, and the Magnum PSI Team2
1
CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK
2
DIFFER, De Zaale 20, 5612 AJ Eindhoven, Netherlands
3
Sandia National Laboratories, Albuquerque NM 87185, USA
Recent experiments on
Magnum-PSI exposed a
lithium-filled heat pipe to a
hydrogen plasma beam to
demonstrate the potential
of radiatively cooled, high
temperature heat pipes as
Figure 1: Temperature image of a heat pipe (side view) under plasma load modular, replaceable
in Magnum-PSI, obtained with webcam-based thermography. The plasma
beam is impinging horizontally from the right of the image. plasma facing components.
Monitoring the temperature distribution over the full 20cm length of the pipe was a crucial
element of the experiment, requiring wide field-of-view infrared thermography diagnostics
able to operate in the confined space and high magnetic field in the bore of the Magnum-PSI
superconducting magnet. Here we present the development of a near-infrared (NIR)
thermography system based on commercial high-resolution webcams (1920x1080 pixels) for
this purpose. By removing the webcams’ internal NIR blocking filter and replacing it with an
external bandpass filter of λ = 1.07µm, FWHM = 10nm, the cameras are sensitive for
thermography over the temperature range ~500 - 1900℃ (for emissivity ε = 0.4). The voice
coil motor auto-focus mechanism was removed from the webcams to enable operation in
high magnetic fields, which was successfully demonstrated at up to 1T. A laboratory black
body source was used for absolute calibration, after characterisation of the camera response
curve shape in visible light. Python software for low frequency data acquisition (~1.25Hz)
has been developed and provides live calibrated images, temperature plotting and the ability
to issue simple temperature-based alarm signals over a serial port for overheating protection.
Two of these cameras were used in the Magnum PSI heat pipe experiments, with an example
image from one camera shown in figure 1. We will present details of the diagnostic
development; calibration & data analysis methods, and example results from this experiment.
