Speaker
Konstantin Vukolov
(Kurchatov Institute)
Description
Silica-based optical fibers have a high light transmission in visible range and so they are widely used for transmitting the light from plasma to detectors in modern thermonuclear facilities. The fiber bundle is comprised as a rule of several tens or hundreds optical fibres of 100-500 microns diameter. The lifetime of the optical fiber in ITER should be more than 15 years. Radiation resistance is a major problem for fiber optics in ITER because of the light transmission has to be adequate to allow measurements up to the end of DT mode.
The report is devoted to problems of the development of fiber optics for ITER diagnostics. Options for fiber bundle are considered on the example of H-alpha diagnostics. Fiber bundles start in the port cell held there for about 6 m to a concrete wall and then extend up to the diagnostic room at a distance about 130 m. The results of neutron fluxes calculation at the location of the fiber bundles are given in the report.
A brief review is presented of the irradiation tests of optical fibers. The opportunities for optical fiber radiation hardening or annealing are discussed. It is shown that the pure silica-core/F-doped silica-clad fibers are the best from point of view of radiation resistance in ITER. Of course, these fibers are not perfect, because they suffer from radiation-induced optical absorption and luminescence. To improve the behavior of optical fibers under irradiation they must be in the place already well protected from neutron flux. Analysis of the irradiation tests and neutron calculations shows that the radiation resistance of modern optical fibers provides the opportunity for its application in ITER in the spectral range 450-1300 nm.
Co-authors
Aleksey Gorshkov
(Kurchatov Institute, Moscow, Russian Federation)
Konstantin Vukolov
(Kurchatov Institute, Moscow, Russian Federation)
