The Low Energy high intensity heavy ion Accelerator Facility (LEAF), independently developed by the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS), passed the expert panel acceptance inspection organized by the National Natural Science Foundation of China on December 9.

Heavy-ion accelerator can accelerate ions heavier than alpha particles. As advancements in accelerator technologies continue, research in ion beam physics has significantly deepened our understanding of the universe, leading to widespread applications across various fields.

As the world's first stand-alone low-energy, high-intensity heavy-ion accelerator facility, LEAF offers exciting prospects for interdisciplinary research in areas such as atomic physics, nuclear astrophysics, and nuclear energy materials.

LEAF is designed for multifunctionality and miniaturization, consisting of several advanced subsystems, including a 45 GHz superconducting highly-charged electron cyclotron resonance (ECR) ion source, a high-voltage platform, a high-intensity multi-charge-state beam analysis and preparation system, and a continuous-wave radiofrequency quadrupole (RFQ) heavy-ion accelerator.

"LEAF can provide intense heavy-ion beams and mixed ion beams of various charge states from light to heavy elements, offering numerous advantages such as high beam intensity, high charge state, diverse ion species, and a wide range of energy variations," said ZHAO Hongwei, the chief scientist of the project and an academician of CAS.

After nearly a decade of dedicated effort, IMP researchers overcame a series of technical challenges related to the production and low-energy acceleration of intense highly-charged heavy-ion beams.

For the first time, the team applied Nb3Sn superconducting magnets to ECR ion sources and developed a 45 GHz highly-charged ECR ion source that operates at the highest magnetic fields and microwave frequencies. This innovative ion source achieved a beam current intensity of 350 microamperes for ²⁰⁹Bi³⁵⁺, setting a new world record.

"The ECR ion source we developed can produce a beam intensity more than twice that of similar devices in the world, laying a solid foundation for developing next-generation high-intensity heavy-ion accelerators," said Prof. SUN Liangting from IMP, who led the superconducting ion source development for LEAF. 

The researchers also developed a high-intensity continuous-wave RFQ heavy-ion accelerator, capable of accelerating and stably operating highly-charged heavy-ion beams at the milliampere level.

With LEAF, scientists are expected to conduct pioneering experimental research on low-energy, highly-charged ion collisions. They will be able to directly measure key nuclear reaction cross-sections related to nuclear burning processes in various stellar objects, addressing long-standing scientific questions in nuclear astrophysics.

In addition, LEAF can also be used to conduct fast evaluation and screening of nuclear irradiation resistant materials, facilitating the development of new materials with superior radiation resistance to meet the urgent demands of next-generation nuclear energy initiatives.

Figure 1. Schematic diagram of LEAF (Image by IMP)

Figure 2. The Low Energy high intensity heavy ion Accelerator Facility (Image by IMP)

Figure 3. 45 GHz superconducting ECR ion source (Image by IMP)