The synchrotron radiation for industry

The synchrotron radiation is the electromagnetic beam (light) emitted by charged particles (electrons) circulating at high speed in a ring where there is a very high vacuum.  Originally considered a parasitic phenomenon by high energy physicists, who measured the structure of atomic nuclei, during the last three decades the beam has become a major source of light used each year by thousands of researchers and engineers across the world in all disciplines for the exploration of matter, from pharmacology to aeronautics.
 

This success stems from its remarkable properties: spectral continuity over a range from infrared to X-rays, weak divergence of emission in the vertical plane, flux and luminance billions of times greater than those of classic sources of X-rays, polarization in the horizontal plane, temporal structure in pulses, and a certain spatial and temporal coherence.
 
 

Sources of synchrotron beams are magnetic devices arranged along the length of the ring where electrons are accelerated, or magnets placed between two straight sections of the ring (made up of a dozen to around forty straight sections according to size), or of devices placed in the middle of a straight section consisting of a series of magnets of alternating polarity, provoking a series of short-term deviations, thus strengthening luminosity (an undulator, or wiggler). 
The beam is emitted tangentially in the ring by each magnetic device, in the form of horizontal layers with very little divergence; it is extracted via windows situated regularly along the length of the ring.  Each beam thus feeds into a measurement station dedicated to a particular material analysis technique.

A measurement station called a beamline is composed of three chambers.  The closest one to the source holds the components of the optic that store the beam: a monochromator to transform the white beam into a monochromatic beam; mirrors to filter and focus.  The beam is then captured in the chamber where measurements are taken place, the chamber that contains the optic components of additional focus and measurement banks (sample holder, goniometer, detector).  Finally, longer-distance measurements are taken in the next chamber by teams of  engineers and scientists.
 

 

The main use of synchrotron light beams is the characterization and analysis of materials.  All techniques based on the interaction between luminous photons, infrared to X-rays, and matter are based on this, aside from the range of visible light, for which lasers pose no competition.  Techniques based on the principal types of light-matter interaction (diffraction, absorption and reemission) give access to morphological, structural, chemical, or electronic information. 
Synchrotron light is also important for certain types of insulation, especially for the manufacturing of micro-objects by lithography, calibration of detectors, or as sources of photochemistry.
 

In comparison with the same techniques conducted in laboratories with conventional sources of light, use of the synchrotron source offers new perspectives, especially for microanalysis and imagery via scanning at the micro- or submicrometric level, made possible by the weak divergence of the beams, or for the monitoring of kinetics in real time thanks to the very high flux of photons, down to the microsecond.  But there are also techniques proper to synchrotron light, especially those that necessitate a continuous spectral range, such as X-absorption spectroscopy. 
Other than these performance-related benefits, another reason to use synchrotron techniques resides in the possibility of coupling them to each other, sometimes carrying out simultaneous measurements, which considerably increases the amount of information that can then be extracted.
 

The all-too-widespread idea that fundamental research is done only in synchrotron ray centers is false.  Researchers and engineers from the industrial world are always surprised when the products and subjects analyzed by their colleagues are listed, such as, for example, the aging of chocolate, the baking of bread, the stability of food mousses, the effect of cosmetics, control of plastic bottles, control of microelectronic devices, strains on turbine paddles, treatment of pollutants, or the development of new medications.  In reality, industrial and applied activities represent more than one quarter of the use of lightbeams.  All the phases of the life of a product are involved: R&D, manufacturing and control, and aging and recycling.

The synchrotron beam has given rise to a blossoming development of varied uses.  In spite of the supply, which is continuously increasing with the putting in service of new synchrotrons all over the world (today there are around twenty in operation), the demand for access time remains unmet, since the number of users continues to grow.