We demonstrate that secondary ions sputtered from a macrocapillary's inner surface by the primary beam induce premature saturation of the guiding field, hindering fast ion guiding. By suppressing secondary ion sputtering with grooved surfaces, we achieve a guiding-field potential difference exceeding 1 kV, 2 orders of magnitude larger than previously achieved in stable ion guiding. This enables stable guiding of a 20-keV/q O^{5+} beam at offset angles up to 15°, with transmitted ions retaining their initial energy and charge state. A self-consistent field model accurately reproduces these results, revealing that guiding performance relies on managing secondary ions and the channel's voltage tolerance, while remaining robust against beam fluctuations. This Letter paves the way for ionic fibers that, much like optical fibers for light, passively and adaptively control ion transport.

Abstract Gasdynamic ion sources are capable of producing high current ion beams with low-to-medium charge states. It is proposed to pre-accelerate tens of emA ion beams with low-to-medium charge states produced by a gasdynamic ion source, and then to strip them to high charge states to meet the increasing requirements of advanced heavy ion accelerators for high-intensity ion beams. As the first step to investigate this scheme, a 45 GHz gasdynamic ion source which operates in pulsed mode has been developed. It’s first ion beams with the intensity of several hundred mA/cm 2 have been extracted, which demonstrates its potential of intensive beam formation. The electron temperature and density were diagnosed with the measurements of the leaking electron current and the line intensity ratios of EUV spectra.

Abstract Heavy ion synchrotron accelerators rely on intense pulsed beams of highly charged ions. The production of these pulsed beams from an electron cyclotron resonance (ECR) ion source is primarily achieved using the afterglow mode. To further enhance the ion source performance in afterglow mode, a novel technique known as the pulsed biased disk has been developed at the Institute of Modern Physics (IMP). The effect of this pulsed biased disk on the xenon afterglow beam currents has been experimentally investigated using a superconducting ECR ion source. The experimental results and conclusions derived from the data are presented in this article.

The high-frequency, high-gradient, low-β accelerator structure is a key technology enabling compact ion linacs for hadron therapy, garnering significant interest in cancer treatment research. Currently, multiple institutions globally are advancing this technology. However, the achievable accelerating gradient remains limited to approximately 50 MV/m due to radio-frequency (rf) breakdown (BD) limitations. To enable higher accelerating gradients, researchers at the Institute of Modern Physics, Chinese Academy of Sciences, have proposed and designed a low-β high-gradient cryogenic copper cavity targeting a theoretical accelerating gradient of 60 MV/m with a specified breakdown rate (BDR≤10^{−6} bpp/m). This paper details the design, fabrication, and tuning methodology of a β=0.3 cryogenic traveling-wave high-gradient accelerating structure. Cell tests were performed to verify the cryogenic performance of the cavity. Upon cooling from room temperature to 77 K, the cavity’s quality factor (Q) increased by a factor of 2.9, while its resonant frequency shifted upward by 9.85 MHz. Subsequently, a 15-cell cryogenic traveling-wave structure was fabricated and tuned to meet stringent design specifications. The conduction cooling methodology was experimentally validated, achieving a stable cavity temperature of 77±0.3 K within 5 h. This work establishes a framework for tuning cryogenic traveling-wave copper cavities and implementing conduction cooling in high-gradient systems.

To investigate the radiation resistance of multilayer graphite (MLG) prepared by the methods of vacuum-assisted self-assembly (VASA) and graphitization of polyimide (PI), irradiation experiments were carried out using 3.9 MeV/u Xe ion beams at fluences up to 1 & times; 1015 ions/cm2, comparing with graphene oxide (GO) and diamondlike carbon (DLC). These materials are potential candidates for charge stripping in modern accelerators, where they must withstand increased beam intensities and provide reasonable service time. Characterization was carried out, including scanning electron microscopy to study surface morphologies, confocal Raman spectroscopy for bonding structures, X-ray photoelectron spectroscopy and X-ray diffraction for crystal structures. Additionally, high-resolution transmission electron microscopy was used to analyse crystallinity and micromorphology, tensile testing for mechanical properties, and laser flash analysis for thermal diffusivity. The MLG foils exhibit negligible change in D-peak intensity, indicating preservation of the graphite structure, with the graphitization degree remaining above 90% after irradiation. These foils also exhibit "ruck and tuck" defects and larger crystallites after irradiation, indicating exceptional radiation resistance relative to the GO and DLC foils. Furthermore, the much higher values of the elongation at break and in-plane thermal diffusivity of the MLG foils explain their superior radiation hardness from the perspective of macroscopic properties.

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding Λ polarization puzzle, in which Λ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton (pp), proton-nucleus (pA), and nucleus-nucleus (AA) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of pA and AA collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

Although RFQ (radio frequency quadrupole)-based axial injection into a high-intensity cyclotron offers several advantages, such as high bunching efficiency and compact design, it requires further research and development (R&D) since it has never been realized before. To support this research, a prototype of a compact RFQ designed for the H2+ beam has been developed. This paper discusses the beam dynamics, RF design, thermal analysis, construction, and RF measurements of the RFQ. The beam dynamics design aims to achieve maximum bunching efficiency at the median plane of the cyclotron. To achieve this, two re-buncher cells are integrated in the exit transition cell of the RFQ. Additionally, the RFQ tank is partially embedded within the cyclotron yoke, allowing it to be positioned as close to the median plane as possible. Considering the operating frequency of 81.25 MHz, a so-called ladder RFQ is proposed. The transverse diameter of the ladder RFQ is less than 300 mm, enabling re-entry into the cyclotron yoke. The ladder RFQ tank has been assembled, and cavity measurements have been completed. The RF measurements show good agreement with the simulations. The frequency matches the design value, and the quality factor Q0 reaches 92.3 % of the simulated value. The quality of the electric field is evaluated using the perturbation method. Gravity-induced errors of the perturbation bead were corrected by averaging the fields across different quadrants. Consequently, the un-flatness of the electric field in the longitudinal direction is +/- 3 %. The dipole field component ranges from-3 % to 3 % in the front section and is nearly zero in the latter half of the cavity.

Charge exchange (CX) x-ray spectroscopy is a vital diagnostic tool for astrophysical and fusion plasmas, yet its accuracy is limited by uncertainties in the orbital angular momentum (l) distribution of captured electrons. This study presents a systematic evaluation of prevalent l-distribution models through laboratory measurements of L-shell x-ray emission from Ar16+ colliding with He at energies of 1.2-10 keV/u. The measured x-ray spectra and relative line ratios are compared with theoretical results that are calculated with the use of n-resolved CX cross sections derived from the multichannel Landau-Zener method combined with various analytical l-distribution models and cascade deexcitation branching ratios. A systematic comparison reveals that the statistical l-distribution provides the best approximation to the measured spectra across the energy range considered. This work provides reliable atomic data for spectral models that can be used in astrophysical and fusion plasma diagnostics.

Extended bunch spacing is required for precise product detection in certain nuclear physics experiments. To fulfill this need, a prototype RF chopper system was developed for the Low Energy Heavy Ion Accelerator Facility (LEAF) to provide an approximately 100 ns clean gap in the beam structure. The chopper operates at 5.078 MHz, employing a quarter-wave coaxial resonator. The RF design predicts that driven by an RF power of 217 W, the chopper system attains a deflection angle of approximately 11 mrad at a deflecting voltage of 20 kV for ions with a mass-to-charge ratio of 4, thereby facilitating the selection of one bunch out of every eight. This paper presents the design, construction, and low-power RF validation of the chopper prototype.

The line ratios in X-ray emission resulting from charge exchange between highly charged ions (HCIs) and neutral atoms are not only crucial for accurately modeling astrophysical X-ray emissions but also offer a unique perspective on the charge exchange processes happening during collisions. The K X-ray spectra following charge exchange between Mg11+ and He are presented for a collision velocity of 1489 km/s (11.5 keV/amu). The spectra were measured by two Silicon Drift Detectors capable of resolving the Mg10+ Kα, Kβ, Kγ, and Kδ+ lines. The line intensity ratios of Kβ, Kγ, and Kδ+ relative to the Kα line, as well as the hardness ratio, were obtained. The experimental results were compared with the theoretical results from a cascade model that utilizes the state cross-sections produced by multichannel Landau–Zener (MCLZ) calculation. It was discovered that the K X-ray spectrum features can be reproduced well by MCLZ theory when the contributions of both single electron capture (SEC) and autoionizing double capture (ADC) processes are included. This finding implies that the ADC feeding mechanism is significant and should be taken into account for the X-ray emission during charge exchange between highly charged ions and multielectron atoms.

A comparative study was conducted to investigate the synergistic effects of H and He on the microstructure evolution, irradiation swelling, and hardening of two candidate ferritic/martensitic steels (SIMP and T91) for fusion reactors and spallation target. Ion irradiation experiments were carried out using mixed H2+/He2+ beams with doses of 4 x 1017 H2+/cm2 and 1 x 1017 He2+/cm2, at irradiation temperatures of RT, 300 degrees C, and 500 degrees C. The results reveal that at low temperatures, H and He interacted to form stable H-He-vacancy clusters, promoting uniform cavity nucleation. As the temperature increases, the cavities were more heterogeneously distributed, particularly at grain boundaries (GBs) and dislocations. Notably, SIMP exhibited superior resistance to irradiation swelling compared to T91, likely due to its finer microstructure and higher silicon content. The study also shows that the hardening of SIMP was more pronounced than T91, correlating with larger size and higher density of dislocation loops (DLs). The irradiation hardening decreased with increasing temperature. These findings reveal a temperature-sensitive synergy between H and He, emphasizing its significance for material design in fusion and spallation environments.

In the high-energy mode of Booster Ring (BRing) of the High Intensity heavy-ion Accelerator Facility (HIAF), the pre-accelerated ions from the iLinac will be stripped by a carbon foil to higher charge states and then injected into the BRing. The thermal deposition and irradiation damage caused by high beam intensity and high energy deposition limit the lifetime of the foil. To ensure the stable operation of HIAF, a long-lifetime stripper foil with excellent irradiation and high-temperature resistance is required. This report aims to reveal the irradiation damage evolution of several kinds of carbon foils and its impact on their physical properties. Irradiation experiments were performed at HIRFL-SFC using Xe beams with the energy loss close to that of U beams in HIAF. There were three kinds of foils from four producer irradiated in the experiments, including Multilayer graphene (MLG) produced by KANEKA Co. and the Institute of Coal Chemistry (SXICC), diamond-like carbon (DLC) foil by the Institiute of Modern Physics (IMP) and Graphene Oxide (GO) foil by TIMESNANO Co. Various characterization methods were used to study the changes in surface morphologies, microstructures, and physical properties of the foils. The results indicated that MLG has a tendency for amorphization, DLC has a tendency for graphitization, and the oxygen-containing functional groups on the GO surface are damaged. These structural changes are expected to significantly impact the mechanical properties of the foils.

To meet the increasing demands for Highly Charged Ion Beams(HCIB) in new and existing heavy ion accelerators, we propose the Ion TRap for high Intensity Pulse beam (ITRIP). ITRIP aims to convert a DC ion beam from an Electron Cyclotron Resonance Ion Source (ECRIS) into a high-intensity, short-pulsed ion beam with suitable compression ratios. The conceptual design of ITRIP, inspired by Electron Beam Ion Sources (EBIS), features a simple trap consisting of an electron gun, a solenoid, and a set of Drift Tubes (DTs). Ions injected from an ECR ion source are trapped radially and axially within the ITRIP. By controlling the potential of the drift tubes, highly charged ions can be accumulated through multiple injections and extracted in pulses of tens of microseconds. To verify the principle of ITRIP, a dedicated ITRIP prototyping platform has been developed. The key issues of ITRIP, including beam injection,beam accumulation and pulsed extraction properties, have been tested and analyzed. Preliminary results and conclusions have been obtained, demonstrating the feasibility and performance of ITRIP as a novel ion trap for generating pulsed high-intensity highly charged ion beams. In this paper, a general overview of the ITRIP concept, its design, and the experimental verification conducted with the platform will be presented.

We studied the stability and reliability of an 39Ar enrichment device for 39Ar dating. By integrating the 39Ar enrichment device with an Atom Trap Trace Analysis (ATTA), we enriched and cross-validated 21 samples of varied compositions to evaluate the performance of the 39Ar enrichment device. Experimental results indicate that the enrichment process is highly repeatable, with stable and reliable results across multiple samples. Based on these findings, we further evaluated the device's capability for circulation enrichment. Experiments indicate that circulation enrichment significantly enhances enrichment efficiency. These studies demonstrate that the 39Ar pre-enrichment system is capable of bulk enrichment for dating samples. Furthermore, cyclic enrichment enables precise analysis of ancient samples with low 39Ar abundances and significantly extends the dating range of 39Ar.

Heavy ion synchrotron accelerators rely on intense pulsed beams of highly charged ions. The production of these pulsed beams from an electron cyclotron resonance (ECR) ion source is predominantly achieved through the afterglow mode. However, the influence of microwave parameters on the characteristics of afterglow beams in high-frequency, high-power, and large plasma-volume ion sources remains unexplored. Recently, a series of experiments have been conducted with a third-generation superconducting ECR ion source. The effects of key microwave parameters, including the power level and pulse length of the secondary microwave source, as well as the RF-off time of the primary microwave radiation, on xenon afterglow beam currents are systematically examined. The experimental results and conclusions derived from the data are presented in this article.

To fulfill the normal operational requirements of the fourth generation electron cyclotron resonance ion source (FECR) superconducting magnet, a cryostat in the form of liquid helium immersion was designed based on several Giffod McMahon cryocoolers. Considering the substantial number of current leads (a total of 9) and the high current value (with the maximum current of 709 A) of the superconducting magnet, a dedicated current lead test platform was designed and constructed to ensure operational stability and thermal management of the cryostat. This platform was utilized to conduct comprehensive tests on the high temperature superconductivity (HTS) leads and room temperature copper leads intended for use in the cryostat, including quantitative evaluation of conductive heating load and Joule heating load under operational conditions. The test results demonstrate that the designed leads can meet the normal working requirements of the FECR cryostat, achieving a maximum current capacity of 720 A with heat load of 28.88 W per copper lead and 0.12 W per HTS lead, respectively.

Highly oriented pyrolytic graphite (HOPG) is frequently adopted as the reaction target in ^12 C+ ^12 C fusion reaction experiments owing to its superior purity. In this study, we investigate the reaction yield dependence on the accumulated beam dose on HOPG target using a novel detection system consisting of a time-projection chamber and silicon array. The reaction yields are significantly reduced under intense beam bombardment owing to radiation damage to the HOPG surface. The α _0 and p_0,1 yields decrease by 51.5 ^12 C ^2+ beam dose accumulates at 5 C. Using the novel detection system and HOPG target, the α _0 yield is determined to be 2.68^+4.69_-1.69 × 10^-17 / ^12 C after correcting for the yield loss due to radiation damage. Our result represents the highest sensitivity achieved to date in direct measurements of ^12 C( ^12 C, α _0 ) ^20 Ne.