A new radiation-hard endoscope for divertor spectroscopy on JET

► A new radiation-hard endoscope with optimised divertor view has been developed on JET. ► A high optical transmittance (≥30%) in the operating wavelength range from 390nm to 2500nm has been achieved. ► The endoscope delivers high spatial resolution ≤2mm at the object plane and ≤3mm over the whole d...

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Bibliographic Details
Published in:	Fusion engineering and design Vol. 88; no. 6-8; pp. 1361 - 1365
Main Authors:	Huber, A., Brezinsek, S., Mertens, Ph, Schweer, B., Sergienko, G., Terra, A., Arnoux, G., Balshaw, N., Clever, M., Edlingdon, T., Egner, S., Farthing, J., Hartl, M., Horton, L., Kampf, D., Klammer, J., Lambertz, H.T., Matthews, G.F., Morlock, C., Murari, A., Reindl, M., Riccardo, V., Samm, U., Sanders, S., Stamp, M., Williams, J., Zastrow, K.D., Zauner, C.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-10-2013
Subjects:	Carbon Design engineering Divertor Endoscope Endoscopes Impurity radiation ITER Mirror based optics Monitors Optical design Spectroscopy Tungsten Ultraviolet Walls Mirror based optics Spectroscopy ITER Divertor Impurity radiation Endoscope
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Summary:	► A new radiation-hard endoscope with optimised divertor view has been developed on JET. ► A high optical transmittance (≥30%) in the operating wavelength range from 390nm to 2500nm has been achieved. ► The endoscope delivers high spatial resolution ≤2mm at the object plane and ≤3mm over the whole depth of field (±0.7m). ► The new optical design includes options for the in situ calibration of the endoscope transmittance. ► A new type of shutter based on pneumatic techniques has been developed in view of ITER and integrated into the endoscope. In preparation for ITER, JET has been upgraded with a new ITER-like wall (ILW) whereby the main plasma-facing components, previously made of carbon, have been replaced by Be in the main chamber and W in the divertor. A new endoscope with optimised divertor view has been developed in order to survey and monitor the emission of specific impurities such as tungsten, beryllium and the possibly remaining carbon in the tungsten divertor of the JET-ILW. It operates in the wavelength range from 390nm to 2500nm with high optical transmittance (≥30%) as well as high spatial resolution, that is ≤2mm at the object plane and ≤3mm over the whole depth of field (±0.7m). The endoscope is a prototype for testing an ITER relevant design concept based on reflective optics only. The endoscope has an optimised observation in the near ultraviolet and in the blue spectral region to ensure the detection of the W I-emission line at 400.8nm. In parallel to the new optical design, a new type of ITER-like shutter system based on pneumatic techniques has been developed and integrated in the endoscope head. The new optical design includes options for an in situ calibration of the endoscope transmittance during the experimental campaign.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0920-3796 1873-7196
DOI:	10.1016/j.fusengdes.2013.02.053