Fiber Optics to prevent accidents in mines and power plants
Friday, Aug 18, 2017
NUST MISIS scientists have suggested a technology for the creation of high-precision sensors based on doped fiber optics for accident prevention in the nuclear, space, and mining industries.  

"An international team of scientists led by Alexander Kir`yanov, a visiting Professor at NUST MISIS's Semiconductor Electronics and Semiconductor Physics Department, in cooperation with the Center for Research in Optics (Leon, Mexico) and CSIR-Central Glass & Ceramic Research Institute (Kolkata, India) has developed a technology for the creation of high-precision stand-alone sensors based on fiber optics," said Alevtina Chernikova, Rector of NUST MISIS.

The created fiber optics is doped with rare-earth and transition metals: erbium, holmium, bismuth, etc., in addition to nanoparticles of silver and silicon. The composition and ratio of ligands (chemical additives) in quartz-based fibers are unique, as they provide unique properties in obtained fibers. The study's results have been published in the journal LaserPhysicsLetters.

The high sensitivity of the resulting fibers to temperature changes, tension, chemical composition, and an environment's background radiation, as well as their stability in inhospitable environments and their high resistance to electromagnetic disturbances allows the fibers to carry out high-precision monitoring of large-scale facilities (pipelines, drillings, power plants, bridges) on a number of parameters. The length of fiber optics also gives the chance to measure large size objects (up to hundreds of meters). In near-earth orbit, sensors based on these obtained fibers can measure the conditions of background radiation in spacecrafts.

Sensors based on these fiber optics effectively register various types of radiation emissions in a wide range of doses, and can do so with high-precision in ultra-high (up to 1700°С) temperatures, harsh chemical compositions, and powerful electromagnetic fields. The length of fiber optics allows the technology to carry out remote measurements; for example, it can provide full-scale monitoring of deep oil wells, mines, and pipeline assemblies for nuclear plants. Due to its unique characteristics, devices based on this technology will be in high demand in a plethora of fields, including construction and geotechnical engineering, the aerospace and oil & gas industries, and high-current energy engineering, including nuclear engineering.

"A fiber optic sensor is either a small-sized ("pointed") device (which, in turn, can be a part of a multi-component detecting network, or an interrogator), or a " spatially-distributed circuit" which is able to collect information about detected parameters at great distances - due to fiber's property as a fundamentally "long" environment. In the former case, the sensitive elements of sensors can be Bragg gratings (spectrally-selective filters), written in fiber. Their parameters, i.e. reflection and transmission spectrums, greatly depend on the state of the environment (pressure, temperature, deformation, etc.), and respectively serve as the basis of detection. The entire length of a used fiber is the sensitive element in "long sensor" format. It is used either in "passive" mode (in this case, for example, the changes in absorption and transmission spectrum of doped fiber optics are detected parameters), or "active" mode, when it is a component of a laser (in this case, for example, relaxation frequency, optical spectrum, or laser oscillation mode are detected parameters).  

"Our research, within this project`s framework, is aimed at the creation, comprehensive research, and application of fiber sensors of the second type with the use of specially developed doped fibers, obtained, in particular, by the method of nano-engineering. Such fibers can become a reliable solution while working in an aggressive environment, when the device based on them is in extreme conditions - for example, when thermo-monitoring oil wells or performing dosimetry at power plants," told Alexander Kir`yanov, the head of the project.

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