AR Technology Part 2: Visiting the Hefei Advanced Light Source

The Hefei Advanced Light Source (HALF) is a fourth-generation synchrotron radiation source based on a diffraction-limited storage ring. Its emittance and brightness indicators are designed to be the best in the world. Once completed, it will be the most advanced diffraction-limited storage ring light source in the world.

(Image source: Baidu Encyclopedia)

Why do we need to build advanced light sources? The minimum length that the human eye can distinguish is about 0.1 mm. The reason why our eyes can see objects is that visible light shines on objects and reflects and focuses the light on our retina, so that our eyes can see the objects. However, if the objects we want to observe are very small, smaller than the wavelength of visible waves, the visible waves cannot be reflected when shining on the objects, and we cannot see the tiny objects clearly. Therefore, when we want to observe microscopic objects, short-wavelength light sources are necessary.

In fact, the essence of light is a stream of photons in a specific frequency band. The light source emits light because the electrons in the light source gain extra energy. If the energy is not enough to make it jump to an outer orbit, the electrons will accelerate and release energy in the form of waves. Different wavelengths of light have different uses. Therefore, in order to explore microscopic materials, Chinese scientists have developed a synchrotron radiation source. Simply put, a synchrotron radiation source is a large X-ray machine. The wavelength of light it emits allows us to study the microstructure of materials, providing important support for basic and operational research in materials science, energy environment, and medical environment.

How does such an important scientific device work? The Advanced Light Source has three main components: the linear accelerator, the storage ring, and the beamline test station. Now that we know its main components, let's take a look at what each of them does.

The function of the linear accelerator is to provide the electron storage ring with the required electron storage beam. The electron beam with an energy of 100,000 electron volts generated by the electron gun is first accelerated to 150 million electron volts by the linear accelerator, which is about 40 meters long, and then injected into the booster with a circumference of about 180 meters. The booster continues to accelerate to 3.5 billion electron volts, and then is injected into the electron storage ring through the injection/extraction system. This injector that accelerates the electron beam to the operating energy of the electron storage ring is called a full-energy injector. The entire injection process must be "precisely directed" by a specially designed timing control system.

Storage ring, the electron storage ring is a closed circular high-tech device with a circumference of 432 meters, equivalent to a school playground with a 400-meter circular track, used to store 3.5 billion electron volts of high-energy electron beams. The electron storage ring is the main body and core of the synchrotron radiation source, and its performance directly determines the performance of the synchrotron radiation source. It consists of an ultra-high vacuum chamber with a vacuum degree of 10-10 gross, a high-precision magnet system, a high-frequency acceleration cavity, a highly sensitive beam detection instrument and a control system. The high-precision magnet system is the main component of the storage ring, including 40 dipole deflection magnets, 200 quadrupole focusing magnets and 140 sextupole chromaticity magnets.

The beamline experimental station is a comprehensive technology platform for scientists and engineers to use synchrotron radiation to uncover scientific secrets and develop high-tech products. Here, synchrotron radiation is "irradiated" onto various experimental samples, while scientific instruments record various reaction information or changes of the experimental samples, which are processed by high-speed computers and turned into a series of curves or images that reflect the mysteries of nature.

The Hefei Advanced Light Source has a lot of national needs in various fields, including the energy industry chain, food security, national defense security, etc. In terms of industry, it is also the foundation of innovation capabilities and promotes industrial upgrading. For example, in the field of information and communication, people can study future quantum devices, as well as lithography technology, lightweight materials in new materials, life and health, and other fields.

In the future, Advanced Light Source will be the brightest light for us to explore the microscopic world.