Optical Sensors for ITER Fusion Experiment in Unique Application

The ITER Project: the way to new energy

The ITER project for fusion is a large-scale scientific experiment that aims at developing a new, cleaner, and sustainable source of energy, by producing commercial energy from fusion – the process that occurs at the core of the Sun. It involves the construction of a Thermonuclear Experimental Reactor which is being built in Cadarache, France.  Every second, our Sun turns 600 million tons of Hydrogen into Helium, releasing an enormous amount of energy. In ITER, the fusion reaction will be achieved in a Tokamak device, a next-generation fusion machine that uses magnetic fields, including large super-conducting magnets, designed to harness the energy of fusion, i.e., to contain and control the hot plasma. The fusion between Deuterium and Tritium (D-T) will produce one Helium nuclei, one neutron and energy. The energy will then be transformed into heat, required to produce steam, which would then– by way of turbines and alternators – produce electricity.

Problem Sensing systems to be installed in the super conducting coils and on a vacuum vessel of the ITER Project, operating under vacuum, radiation, large electromagnetic fields, and cryogenic temperatures, were required.

 

Solution The aim of the first contract was to provide and install optical sensors capable of bearing particular environmental constraints on different mechanical structures of  superconducting magnets. In total, approximately 500 to 900 sensors together with the related data acquisition systems were developed, produced and delivered. 

 

Result This contract was successfully achieved and, as a result, HBM just signed a new contract for the qualification and supply of optical sensing systems for the ITER’s vacuum vessel. 

The ITER vacuum vessel is a complex structure, which weighs around 5,000 tones. It is located inside the cryostat of the ITER device, and its basic function is to operate as the chamber that hosts the fusion reaction. Within this torus-shaped vessel, plasma particles collide and release energy without touching any of its walls due to the process of magnetic confinement. The vacuum vessel will operate at a temperature close to 100 °C and at a nominal water pressure in the inter-space of 11 atmospheres, equivalent to the underwater pressure at 110 meters. Due to its complexity and size, the construction and monitoring of such massive structure involve a high degree of precision. Thanks to the massive testing involved in this project, HBM expects that the sensors qualified in this program will find other applications at ITER and other customers who require measurements in high-temperature, vacuum and radiation environments.

As far the previous contract is concerned, HBM FiberSensing provided strain, displacement and temperature optical sensors to be installed on coils and different mechanical structures of the ITER superconductive magnets. The first phase of the work included the adaptation and qualification of optical sensors, interrogators and software for the particular constraints of the application, including cryogenic temperatures down to 4K, radiation and vacuum. A second phase consisted of series production and delivery of the full sensing systems. In total, approximately 500 to 900 sensors together with the related data acquisition systems were delivered, in addition to complementary accessories such as cables and software. The time frame was as follows:

• Phase 1 — Sensor development and testing.
• Phase 2 — Qualification in the following environments: high radiation; high vacuum and cryogenic - liquid helium temperatures. 2011–2014
• Phase 3 — Sensor Industrialization, production and delivery. 2014–2017