Researchers at the University of Erlangen-Nuremberg in Germany have created a particle accelerator with a length of only 0.2 millimeters, the smallest device of its kind to date, and even small enough to fit in a pen tip. The particle accelerator is the first miniature accelerator capable of producing fast and well-focused beams of electrons that can accelerate electrons to 100,000 kilometers per second, promising applications in the medical field. The results of the research were recently published in Nature.
Side view of a tiny particle accelerator.
Image Credit: Tomá? Chlouba, Roy Shiloh, Stefanie Kraus, et al.
Large Hadron Colliders or particle accelerators used to treat cancer in medical facilities mostly use electric fields and magnets to accelerate particles such as electrons, which are typically generated by radio waves with wavelengths measured in meters or centimeters. Peter Hommelhoff of the University of Erlangen-Nuremberg and collaborators chose to accelerate particles using a different kind of electromagnetic wave “light,” which has a much shorter wavelength, just a few hundred nanometers. This allowed them to shrink the size of the accelerator from a few kilometers wide to less than a millimeter.
To make it, the researchers used thousands of 2-micron-tall silicon columns and arranged them into two parallel lines, each 0.2 millimeters long. To run the accelerator, they shine lasers onto this columnar “runway” from above, while injecting electrons from the side. Light waves from the laser interact with the cylinder to create an electromagnetic field that brings electrons together to form a narrow beam. These clusters of particles accelerate through the structure at a speed of 100,000 kilometers per second.
The team tried to add more columns to the “runway”. When they made a 0.5 millimeter-long version, they found that they could accelerate electrons at a much faster rate, increasing the energy carried by electrons by 43 percent. Hommelhoff said this suggests that accelerators are scalable and can become more powerful while remaining small enough, or integrated on chips or even directly at the end of the fiber.
Pietro Musumeci of the University of California, Los Angeles, said that although some micro-accelerators have been built before, this is the first device that can not only accelerate electrons, but also confine them in a relatively narrow beam for scientific experiments.
Currently, the new device gives electrons only one millionth of the energy of large accelerators. But Hommelhoff says there may be ways to boost the energy of each electron. He thought it would be helpful to make these columns from a glass material called molten silica, which can withstand stronger laser light.
Hommelhoff said scientists first proposed using light to shrink accelerators in the ’60s, but engineering challenges at the time made it difficult to implement.
“We can eventually shrink accelerators, and we can put them in the nib, we can think about new therapeutic tools for doctors or small sterilization tools for biological labs.” Hommelhoff said. (Source: Li Huiyu, China Science News)
Related paper information:https://doi.org/10.1038/s41586-023-06602-7