Production of 0.5~1.0 emA highly charged heavy ion beams has been requested by worldwide next generation heavy ion facilities, but remains big challenge to the community. Regarded as the most powerful machine to produce high intensity heavy ion beams, ECR ion sources have been used by most of the heavy ion accelerator facilities in the world, which have also greatly boosted their continuous development over the years. Even after more than 50 years since the first prototype ECR ion source was demonstrated, it still retains its vitality in terms of extracted ion beam intensities and charge states. This paper will present the latest progresses of worldwide high performance ECR ion sources. The main contents will focus on new ion source development, high performance operation, new technology research and the perspectives on high beam intensity operation for heavy ion accelerators.

Superconducting magnets are required for electron cyclotron resonance ion sources (ECRIS) to achieve a high charge state and high intensity heavy-ion beam. Several different designs have been, or are being explored to take full advantage of the high current carrying capabilities of superconducting materials. This talk provide an overview of these different designs, mainly based on sextupole-in-solenoid and solenoid-in-sextupole lay-outs, developed in various laboratories worldwide, as well as the innovative close-loop coil design (MARS) currently under fabrication at LBNL. A comparison between expected performance of the different ECR superconducting magnets will be given, and an outlook towards the possibility of implementing new more advanced superconducting materials will be discussed.

In March 2023, the first rare isotope beam (RIB) was successfully extracted from the Isotope Separation On-Line (ISOL) at the RAON heavy-ion accelerator facility. Surface-ionized beams of lithium (Li), sodium (Na), and aluminum (Al), produced by bombarding a silicon carbide (SiC) target with a 70 MeV proton beam, were delivered to the RIB separation and transport system. The production efficiency of Na isotopes from the SiC target was generally satisfactory, and a short-lived isotope, 24mNa (t1/2 = 20 ms), was successfully measured. The performance of the ISOL RIB separation and transport system was validated through on-line experiments with both stable and radioactive sodium beams. The preparation of highly charged ions, meeting the injection requirements for the SCL3 post-accelerator (energies of 10 keV/u and an A/q ratio of < 6), was achieved using the Electron Beam Ion Source (EBIS). The ISOL RIB, 25Na5+, was successfully charge-bred and transported to the post-accelerator. This presentation will discuss the production, charge breeding, and post-acceleration of RAON's first RI beam.

The Argonne National Laboratory electron beam ion source serves as a charge breeder for the Californium Rare Isotope Breeder Upgrade (CARIBU). The source accepts radioactive beams of 1+ or 2+ ions and raises them to a charge state sufficient for post-acceleration in the ATLAS linac. The efficiency of this process impacts the length of each experiment and hence the type and number of experiments which can be run in each program cycle. Recent efforts to improve the charge breeding efficiency have focused on utilizing the closed shell breeding technique for the mid-mass species typical of CARIBU. Charge breeding investigations with stable cesium have demonstrated an absolute efficiency of 72% for Cs27+ and a total device efficiency of 93%.

In this work, we show our current status in the development of an accelerator-based neutron source based on an incident ion-beam of several tens of mA lithium, which realizes the inverse kinematic reaction between lithium-7 and proton: p(7Li,n)7Be. This neutron source is expected to generate forward-directed neutrons. Understanding the neutron distribution and flux is essential for neutron applications. The present study aims to clarify the neutron distribution and flux in the p(7Li,n)7Be case. Generated neutrons were measured to aid in designing the neutron source. Lithium beams from Tandem van de Graaf accelerators at BNL and HZDR were used to irradiate hydrogen-rich targets, such as polypropylene films, to induce the reaction. Liquid scintillators (BC-501) were located around the target to cover different angles, including the forward direction, to investigate neutron angular distribution and fluxes. The results confirmed a significant concentration of measurement signals in the forward direction throughout the experiments. The differentiation between neutrons and gamma rays using a pulse shape discrimination method is underway. Further details will be presented.