Simulation of environment effects on retroreflectors in ITER
Two plasma diagnostics in ITER will use cube-corner reflectors (CCR): poloidal polarimetry and toroidal interferometry/polarimetry. The multichannel poloidal polarimetry system is planned to operate at a wavelength of 118.8mu m. The multichannel toroidal interferometry/polarimetry system is based on a CO2 laser operating at wavelengths of 10.6 and 9.27 mu m. The long term sputtering by charge exchange atoms and/or deposition of carbon-based _or beryllium-based_ contaminant layers can affect the optical properties of the CCR. The role of both these potentially deleterious effects on the CCR operation is analyzed in this article, taking into account the probing beam wavelength and the CCR locations. The conclusion is that for the intended use of a CCR in the poloidal/polarimetry at 118 mu m neither erosion nor deposition should pose a problem. On the other hand, in the toroidal interferometry/polarimetry system operating at 10 mu m, care must be taken to reduce the charge exchange atom flux and it is likely that deposition will occur and could have deleterious effects especially on the polarization properties of the reflected radiation.
Bibliographic Reference: An article published in: Review of Scientific Instruments 76, 083502 (2005)
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://rsi.aip.org/rsi
Record Number: 200518342 / Last updated on: 2005-09-26
Original language: en
Available languages: en