Currently, two X-ray sources are widely used: relatively weak sources (so-called X-ray tubes, used in hospitals and dentists) and potent sources (synchrotrons). Now, a mid-range car has been added with the new compact linear source from Jom Luiten and his team. The classic X-ray tube is based on 19th-century technology, over a hundred years old.
X-rays are generated by ‘shaking’ fast electrons back and forth hard. There are several tricks for this: in an X-ray tube, the electrons are abruptly slowed down in a material, while in the synchrotron, the electrons bend extremely hard in a strong magnetic field.
At the source at TU/e, the speeding electrons vibrate in the field with an intense laser pulse. “The physical principle with which the electrons shake back and forth is the same as with a large synchrotron, whether at a kilometer or micrometer scale,” Luiten explains.
Working with a compact linear source, the team accepts a lower intensity than generated by a circular synchrotron. For example, the particles in this linear source race at 99.995 percent of the speed of light, and in the large versions (such as ESRF), they race at 99.9999995 percent of the speed of light. And it is precisely the very compact particle accelerator that makes this X-ray source so unique.
Luiten: “This mid-range capability also makes this source suitable for looking into paintings, silicon wafers, or biological material without damaging it. In addition, this source is special because the energy of the X-rays can be very accurately adjusted to the material you want to detect. You can ‘tune‘ it to visualize any periodic table element. In addition, the light beam is reasonably coherent. Because of this, the measurements you can make with it are of great accuracy.”
In addition to the research of the Smart*Light 2.0 consortium, work is being done on a compact ‘mid-range’ X-ray source in about five other places around the world. But none of them has a particle accelerator as compact as this one, whose energy can be varied quickly and easily.
