Three-filter colorimetry in DIII--D to measure {ital in} {ital situ} erosion and deposition of plasma facing surfaces
- Institut fuer Plasmaphysik, Forschungszentrum Juelich GmbH, Ass. EURATOM-KFA, POB 1913, 52425 Juelich (Germany)
- General Atomics, P. O. Box 85608, San Diego, California 92186-9784 (United States)
Three-filter colorimetry has been introduced in the DIII--D tokamak to measure {ital in} {ital situ} the growth and the erosion of transparent wall coatings ({ital a}-C/B:H) in the divertor region. Colorimetry uses the interference of light on a transparent layer to measure the film thickness. The colorimetry setup at DIII--D consists of a light source, a black and white camera, and a filter wheel equipped with three broadband color filters. A white light source illuminates the area of interest. A picture with each filter is recorded and digitized. Thus the interference color of a semitransparent layer is measured and the film thickness is computed using the formalism of thin film optics. Since color cameras are more sensitive to neutron damage, a set of three filters was chosen which best matches the responsivity of a radiation-hardened B/W camera. In fact, one infrared filter and two visible filters are used. The three 2D camera images obtained from rotating the three filters into the line of sight of the camera are used to produce a 2D image of the change in film thickness due to the high flux of particles and power incident on the film during a diverted discharge. In a first measurement, the technique was used to measure the growth of a boron film {ital in} {ital situ} in the DIII--D tokamak. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- DOE Contract Number:
- AC03-89ER51114
- OSTI ID:
- 124853
- Journal Information:
- Review of Scientific Instruments, Vol. 66, Issue 11; Other Information: PBD: Nov 1995
- Country of Publication:
- United States
- Language:
- English
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