The China Institute of Atomic Energy (CIAE) is developing a proton cyclotron with an energy of 9.5 MeV and a current of 100 mu A. To evaluate the performance of the cyclotron, the beam dynamics study has been conducted. Static and dynamic orbit analyses combined with phase-space matching were used to assess its beam acceptance and acceleration capability. Particle tracking simulations were employed to calculate characteristics such as radial centering and axial focusing, and the structure was optimized accordingly. The extracted beam parameters were controlled by adjusting the tilt angle of the stripping foil. The phase acceptance of this cyclotron exceeds 60 degrees, and the beam size at the liquid target is 1.35 mm & times; 2.01 mm. The cyclotron has entered the beam commissioning stage, with measured beam currents of 107 mu A at the internal target and 65 & micro;A of extracted beam current at the Faraday cup after stripping.

To address the heavy reliance on imported medical cyclotrons in China，the China Institute of Atomic Energy has independently developed a 10 MeV ultra-compact cyclotron，aiming at achieving localized and low-cost production of medical radioisotopes. The device incorporates key technologies including shallow-valley magnets，an integrated high-frequency and vacuum system，single-pass axial shimming，and an internal Penning ion source. It has a compact footprint of less than 1.4 m3 and a total weight under 7.5 tons，and is designed for high integration and intelligent operation and maintenance. Under working conditions of 10 MeV proton energy with 80 μA beam current，the cyclotron maintained stable operation for 2 h，yielding 18F with an activity of over 3 Ci. This output is sufficient for approximately 15 patient doses，fulfilling the clinical demand. The results demonstrate that this accelerator is reliable，user-friendly，and suitable for in-hospital production of short-lived medical radioisotopes such as 18F and 68Ga.

Magnetic field shimming is crucial for achieving isochronous acceleration in a cyclotron. Matrix methods based on least square fitting are commonly used to calculate the cutting curve of a shimming bar. However, this matrix method becomes inapplicable when dealing with cases of nonlinear shimming effects. An algorithm based on the Gauss-Newton iteration method to address shimming problems with nonlinear effects has been proposed. Numerical and experimental results demonstrate the effectiveness and accuracy of this algorithm. It has been applied to a compact positron emission tomography (PET) cyclotron developed at China Institute of Atomic Energy (CIAE).

As the research work about irradiation effect and neutron measurement requires high-energy neutron with the development in the fields of space exploration, medical treatment and high-energy physics investigation, a beamline of quasi-monoenergetic neutron in the range of 30 similar to 50 MeV based on a proton cyclotron with a maximum energy of 50 MeV is under construction and preparation. We studied the design of this quasi-monoenergetic neutron beamline with a focus on target chamber and collimator. Comprehensive comparison on characters of thermodynamic and nuclear physics between lithium and beryllium was conducted, and lithium was chosen as target material by better performance on quasi-monoenergetic neutron peak. Relevant parametric simulations of lithium thickness were carried out in consideration of efficiency and quality of neutron generation which shows the change on height and width of quasi-monoenergetic neutron peak. Energy loss of incident proton caused by titanium film and argon gas was estimated to provide a reference for the mechanical design of target chamber. Evaluation has been done to show the variation of neutron spectra and fluxes at different positions from the target along with collimators of different lengths, and the collimator length was determined to be 2 m in view of flux and ratio of quasi-monoenergetic neutron peak. All work provides a data reference for the building and operation of the quasi-monoenergetic neutron beamline.

The precise measurement and error compensation technique of the main magnetic field in cyclotron accelerator are important research directions and key components in the construction of the device. Due to factors such as internal defects in the iron material and mechanical processing errors, the non-ideal magnetic field generated by the main magnet of the cyclotron accelerator usually deviates from the required isochronous magnetic field distribution and contains a certain amplitude of harmonic magnetic field. Therefore, in the process of developing a cyclotron accelerator, it is necessary to perform multiple shimming on the non-ideal magnetic field, and ultimately achieve the required distribution by correcting the actual magnetic field. Compared with traditional magnetic field compensation algorithms, this paper proposes an algorithm based on a multivariate linear regression model, incorporating the calculation of the first harmonic magnetic field. This algorithm achieves simultaneous quantitative shimming for both temporal errors in the magnetic field and first harmonic errors, eliminating the need for a separate iterative process for shimming the first harmonic magnetic field. In order to avoid increasing the finite element calculation workload, this paper uses a 1/4 magnet model in the new algorithm to obtain the shape function for the first harmonic magnetic field and the average magnetic field. Simplifying the full model finite element calculation of the main magnet to a 1/4 model can save approximately 80% of CPU time. By using the algorithm proposed in this paper, after three iterations of shimming, the isochronism error of the magnetic field in the 16 MeV cyclotron at the China Institute of Atomic Energy is reduced to the order of 10-4, and the integral sliding phase control of particles is controlled within ±14°, while the magnitude of the first harmonic of the magnetic field is reduced to within 6 Gs. The transverse free oscillation frequency of the magnetic field was also adjusted, improving the axial focusing frequency at large radius positions, allowing the beam to pass through dangerous resonances only at low energy positions and quickly move away from resonance positions. Through the first shimming process, the magnitude of the first harmonic of the magnetic field is reduced, minimizing the coupling of the beam phase space in the transverse direction and avoiding major harmful resonances. Experimental studies have shown that this algorithm has the characteristics of low computational cost for shape function calculations, high shimming accuracy, and a small number of iterations. The algorithm in this article can be further expanded to realize the shimming calculation of any high-order harmonic magnetic field error of the cyclotron.

Fixed-Field Alternating Gradient accelerators (FFAG, also known as FFA) are promising candidates for next-generation GeV-class proton driver with average beam power of several megawatts. In isochronous accelerators, radial tunes are approximately increasing with beam energy in a linear way, and thus the integer resonance crossing problem becomes the major bottleneck of GeV-class isochronous FFAG design. In 2019, China Institute of Atomic Energy (CIAE) proposed an isochronous FFAG conceptual design with capability of producing 2GeV/6MW continuous wave (CW) proton beam. However, this conceptual design shows that the beam size is blown up at high energy region due to the third harmonic magnetic field caused by imperfections. The reason is that the integer resonance vr=3 causes a large coherent oscillation, and this large amplitude is not compatible with the following third order intrinsic resonance 3vr=10. In order to correct the large coherent motion before reaching the 3vr=10 resonance, we propose an idea of integer resonance suppressor (IRS) which intentionally introduces the third harmonic magnetic field. Our calculation shows that third harmonic field of 10Gs is acceptable with proper IRS settings, meaning that the requirements of magnet manufacture and installation can be relaxed. The increased imperfection tolerances will make magnet manufacture and installation much easier.

The compact high-intensity proton cyclotron based on the stripping-extraction method has made great progress and obtained huge applications since the first cyclotron was applicated in 1932 in the world, especially in the field of nuclear medicine. China Institute of Atomic Energy (CIAE) built a 30 MeV compact high-intensity proton cyclotron in the 1990s in China and a series of compact high-intensity proton cyclotrons with energy of 10 MeV, 14 MeV, 100 MeV, 14 MeV/1 mA used in boron neutron capture therapy (BNCT) based on the stripping extraction technology have been developed. The 100 MeV compact high-intensity proton cyclotron (CYCIAE-100) built in 2014 is the largest compact high-intensity proton cyclotron with the higher energy in the world with a maximum current intensity of 520 μA and a beam power of 52 kW. The BNCT cyclotron is also the first high-intensity proton cyclotron with extracted beam reaching the mA level in China. A great progress on the stripping extraction technology used in cyclotrons has been achieved at CIAE during the 60 years development. The codes for stripping extraction studies, such as CYCTR, GOBLIN, STRIP-UBC and COMA, are developed by CIAE too. The study method with the code of GOBLIN for the beam dispersion effect in the stripping extraction cyclotrons was given in detail. The influence of the angle between the stripping foil and the beam to the quality of the extracted beam was analyzed in the paper. The single-turn stripping extraction technology for some special application was used in the stripping extraction cyclotrons. The stripping efficiency and the life of stripping foils were studied in the paper. The beam loss control in the stripping extraction field and stripping probe system were introduced in the end.

RF system is one of the key components of a 2 GeV, 6 MW high power fixed field alternating gradient (FFAG) accelerator being designed at China Institute of Atomic Energy (CIAE). In order to verify the design principle and the engineering feasibility, a scaled-down RF cavity is under construction, which can also be used as the main accelerating cavity for a 100 kW electron irradiation accelerator. By the deflections of several 180 degrees bending magnets, the electrons emitted from the electron gun can pass the cavity for multiple times. Due to the limited length of the cavity, the deflection radius should be as small as possible to ensure more acceleration times and consequently higher beam power, which will make the fringe field effect of the bending magnet be a problem. In addition, the bending magnet should provide beam focusing in both the radial and axial directions of the beam and keep the beam envelope stable during the whole acceleration process. Based on the above reasons, the parameters of the combined function bending magnet, such as the pole face rotations (Liu, 1994), magnetic field gradient and shielding distance, have a great influence on the beam dynamics behavior in the accelerator, which bring great difficulty to the design of the combined function bending magnet. In this paper, the coupling design of the bending magnet with focusing function and the high intensity electron beam for this 100 kW irradiation accelerator will be illustrated in detail.

In this paper, the domestic and international demand and development trend of clinical diagnostic radionuclides are analyzed, and the medium and high-energy cyclotrons, adequate and systematic facilities, and preparation techniques required for the production of medical radionuclides based on solid targets are introduced. This paper focuses on the research and development carried out by some important medical institutions and scientific research institutes in China over the years in the aspects of medium and high-energy cyclotrons, beam transmission lines, high-power irradiation target stations and new medical isotope production processes etc. It also looks forward to some new directions for the development of medical radionuclides in China during the 14th Five-Year Plan period.

为调试100 MeV回旋加速器高功率束流及放射性同位素研制,设计了一条高功率质子束流线及可插拔式高功率束流调试靶.研究了100 MeV回旋加速器引出区色散效应及剥离膜的散射效应,从而优化了光学模拟的初始参数,使得模拟结果更加精确.高功率束流调试靶设计为可插拔式以代替常用固定式调试靶,该靶插入束流管道中时可进行高功率质子束流调试,在拔出时,质子束流可直接轰击束流线终端的靶站以生产放射性同位素.优化了高功率束流调试靶的水冷结构,确保调试靶可承受500μA以上的质子束流.经调试,该束流线可传输最高流强520μA的质子束流.

China’s annual crude steel production in 2014 was accounting for nearly half of the world level. Iron and steel industry is not only the highest energy consumption sector in China, but also one of the top three greenhouse gas emission (GHG) sectors. Consequently, development of green and high efficiency technology for energy conversion has been the attractive topic in these decades. For example, iron ore sintering, a pre-treatment process to prepare porous sinters with suitable permeability and strength for ironmaking in blast furnace, contributes the second highest energy consumption and greenhouse gas emission in iron and steel production. According to the statistical data, reducing 1% energy consumption in sinter plant would save 0.25 million tons of standard coal per year. Using biomass for partial replacement of coke breeze in iron ore sintering process is an attractive technique for achieving green production. Therefore, the concept of partial replacement of coke breeze by charcoal was validated in our research. The results suggested that sintering performance was able to satisfy with actual need at low charcoal proportion. However, sinter strength was weakened due to the damaged heat pattern at high biomass proportion. Aiming at solving the above problem, the gaseous fuel was injected to the melting zone from the top and auto-ignited near the original solid fuel combustion zone. Ultra-lean (0.5% vol.) gaseous fuel injection could significantly extend the melting zone from the upstream and raise the sinter strength, without increasing the energy consumption. It was noted that ultra-lean gaseous fuel which can be recycled from coke oven and blast furnace, etc. Furthermore, the imbalance of heat distribution in sintering bed has been considered to be problematic on both energy efficiency and quality of sintered ores. The gaseous fuel segregation method was firstly proposed by controlling the injecting concentration. The gaseous fuel injecting concentration was increased in upper bed to enhance the weak heat pattern, and decreased in the lower bed to avoid energy

In China, there is a strong demand of the medium-energy proton accelerators for proton therapy. A compact superconducting cyclotron named CYCIAE-230 is currently under construction at CIAE to provide 230 MeV proton beam. In this paper, the investigation and quantitative simulation of beam physics for CYCIAE-230 will be presented in detail, which mainly include: 1. The beam dynamics behavior in the ultra compact central region and the design challenges including the micro PIG ion source, the tips of magnetic poles and RF cavities; 2. the numerical simulation and optimization of the phase slip and tune diagram in acceleration region; 3. the orbit simulation in the extraction region, emphasizing on increasing the turn separation and the resonance study; 4. the fast intensity modulation, control of beam stabilization by a closed-loop feedback, and the basic algorithm for controlling the beam intensity, adjusting the phase and their implementations.

CYCIAE-100, a 100 MeV high current compact cyclotron has been constructed and first beams were extracted in 2014. The machine has 5 beam lines for multi-application purposes. N1, one of the beam lines, is designed for high current beam transportation, for beam dump tests and isotope production. In 2016, a mA proton beam was tested on the internal target. In 2017 and 2018, 200 mu A and 520 mu A proton beams were extracted and transported to the beam dump respectively. In addition to increasing the cw beam power of 52 kW extracted from the machine and transported to the beam dump, this paper will also present the simultaneous dual-beam extraction from CYCIAE-100 and the improvement of the uniformity of the beam spot on the target, which will benefit isotope production.

中国原子能科学研究院回旋中心正在研制一套中能质子辐照装置,提供能量范围在10MeV～50MeV的质子束流,以模拟对航天器有重要影响的空间质子辐射环境.在50MeV紧凑型回旋加速器的基础上,设计了质子束流输运系统,将回旋加速器引出的质子束流,通过降能器等元器件调整到用户所需能量,降能后的质子束经过聚焦、偏转后传输到用户终端.为在靶上得到均匀的大直径束斑,束流线上安装了旋转扫描磁铁,将靶上的质子束流均匀扫开,最终在靶上得到能量10MeV～50MeV可调,质子流强最大10μA,尺寸20cm×20cm的束斑.

There are very strong demand for mid-energy of proton machine recent years due to the surging cancer patients and fast progress of the space science in China. For the applications of proton therapy and proton irradiation, the energy range of proton beam usually is from 200 MeV to 250 MeV, or even higher for astronavigation. Based on the R&D starting from 2009, two construction projects of 230 MeV and 250 MeV superconducting cyclotron, which have been implemented recently at China Institute of Atomic Energy(CIAE). That was started in Jan 2015 for the 230 MeV machine, for the program of proton therapy and space science launched by China National Nuclear Corporation (CNNC), and in Jan 2016 for the 250 MeV machine, for the program of proton therapy launched by the Ministry of Science and Technology of China (MOST). In this paper, the designs for the two SC cyclotrons and their key components, including the main magnet, SC coils, RF system, internal ion source and central region, extraction system, etc, and the construction progress of the machines will be presented.

For the applications of proton therapy and proton irradiation, and based on the R&D starting from 2009, a construction project of a 230-MeV superconducting cyclotron (CYCIAE-230) was launched at the China Institute of Atomic Energy in January 2015. A compact main magnet design with warm iron yokes and a superconducting coil system is adopted to reduce the size and, consequently, to lower the construction and operation cost of the cyclotron. In this paper, the physics design, along with the mechanical design of the main magnet, including the structure of the main magnet is described in detail; then, the construction progress and the B–H curve measurement results of the warm iron over the magnetic saturation region are outlined; the R&D of the superconducting coils system and the design of the field mapping system are also briefly introduced.