High-intensity Ion Research Articles

Studies on deposition of high energy Lu ions on metallic substrates using Multi-collector ICPMS

An in-house developed multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) was used for characterizing an indigenous high-current ion source to be employed for production of high intensity ion beam of lutetium (Lu) ions. The ion source is a critical component of Electromagnetic Isotope Separator (EMIS) facility, which is being fabricated for isotopic enrichment of lutetium in 176Lu. As the ion source is a crucial component of the EMIS facility, it was essential to independently test its performance and optimize its parameters prior to its coupling with other subsystems of the EMIS facility i.e. magnetic analyzer and collector system, which are under development. Studies were carried out to determine the contribution of Lu+ in the total ion beam extracted from the ion source by employing a collector setup at the exit of the ion source. The sample deposition on the collector substrate was analyzed, both qualitatively and quantitatively using MC-ICPMS. The contribution of Lu+ ions to the total ion beam from the ion source was found to be ∼ 25% for the total ion current of ∼ 1 mA at an ion energy of 12 keV. Various parameters viz. Lu collection rate, collection per unit area and collection efficiency for deposition of Lu on various substrates of the collector were established. These studies have helped in understanding the deposition mechanism of Lu on different substrates, which has assisted in selecting appropriate target material and refining the design of the collector assembly. This paper discusses these studies in detail.

New Architecture Design of Magnetic Field Monitoring System Based on HIAF

The High-Intensity Heavy Ion Accelerator Facility (HIAF) is one of China's major scientific and technological infrastructure projects, aimed at providing an internationally leading research platform for nuclear physics, nuclear astrophysics, nuclear energy development, nuclear safety, and materials science. During the operation of HIAF, the high-precision measurement and control of magnetic fields are crucial for the stable operation of core equipment. To meet the high demands of HIAF for precision, real-time performance, and system autonomy in magnetic field measurement, this research designs and implements a high-precision magnetic field measurement system based on the LACCS (Large-scale Accelerator Cluster Control System) architecture. The system integrates advanced hardware and software designs, enabling it to efficiently and accurately complete distributed magnetic field measurement tasks, thus providing technical support for the smooth operation of HIAF.

A versatile setup for hydrogen isotope permeation studies.

The Testbed for Analysis of Permeation of Atoms in Samples (TAPAS) is an experimental setup for ion-driven permeation studies with a focus on investigating wall materials for nuclear fusion devices. A monoenergetic, mass-filtered high-intensity keV ion beam is focused and directed onto the permeation sample by electrostatic ion optics and decelerated to the desired ion energy by a dedicated set of apertures close to the sample. We were able to obtain ion energies as low as 170 eV/D with a D3+ ion beam with an ion flux density of the order of 1020 D/m2s on a beam-wetted area of ∼33mm2. These conditions avoid sputtering of W targets by the ion beam and are representative of the particle flux and energy spectrum impinging on the first wall of a prospective nuclear fusion power reactor. Permeation samples can be heated up to 1000K in an ultra-high vacuum. The design of the deceleration system, together with a high pumping speed in the loading chamber, ensures a low pressure of recycling hydrogen isotope molecules in front of the sample. In addition to ion-driven permeation, TAPAS provides a limited capability for gas-driven permeation at low pressures up to nearly 1mbar. Permeating hydrogen isotopes are detected with a quadrupole mass spectrometer in the downstream ultra-high vacuum chamber. After a detailed description of the setup and calibration procedures for implanted particle flux, mass spectrometer, and neutral gas pressure, benchmark experiments on recrystallized, 50μm thick tungsten foils are shown, demonstrating that diffusion-limited boundary conditions for permeation were reached.

The thermal dynamic simulation and microstructure characterization of micro-arc oxidation (MAO) films on magnesium AZ31 irradiated by high-intensity pulsed ion beam

The micro-arc oxidation (MAO) film on AZ31 magnesium alloy was irradiated by high-intensity pulsed ion beam (HIPIB) at the energy density of 1–5 J/cm2 to enhance its corrosion resistance. The temperature and stress field was simulated by numerical model established by Marc.Mentat software to explore the surface modification mechanism of the irradiated MAO films. The experimental results show that the pores on the MAO film surface decreased, and obvious remelting phenomenon was observed on the irradiated film surface at 4 and 5 J/cm2. X-ray diffraction (XRD) detection indicated that HIPIB irradiation had little effect on the phase structure of the MAO films, except for grain refinement on MgO and Mg3(PO4)2. The wettability of the MAO films changed from hydrophilicity to hydrophobicity by irradiation characterized by contact angle results. From the potentiodynamic analysis, the corrosion potential of irradiated MAO films was significantly higher than that of the original ones, the maximal value of the corrosion potential was obtained at 4 J/cm2, which is increased by 57 mV compared with that of the original ones. The simulated results show that the surface temperature of MAO film increases rapidly during the irradiation process, and the maximum surface temperature reaches the boiling point of MgO 3873 K up to 4 J/cm2. At 4 J/cm2, the MAO film exhibited melting and ablation, with depths of 1.8 μm and 0.6 μm, respectively. The high temperature field and thermal stress by irradiation lead to surface melting of MAO film, which promotes the decrease of the number and dimension of the pores on the MAO film surface. The densification and less porosity of MAO film by HIPIB irradiation inhibited the infiltration of the corrosive liquid to the substrate, which is mainly responsible for the modification of MAO film corrosive performance.

Synergy of high-intensity chromium ion implantation and ion beam energy impact on the zirconium alloy surface

The peculiarities and modes of material modification with high-intensity, high-power density ion beams on the irradiated surface are studied for the first time. Chromium ions are implanted into a zirconium alloy using a 25 kW/cm2, 450 μs beam at the pulse repetition rates within 8–35 pps. Every high-energy ion pulse impact is followed by ultrafast cooling of the surface due to heat removal into the target material. Three modes are studied at the temperatures of 580, 700, and 900 °C with an additional pulsed heating. An increase in the average target temperature from 580 to 700 °C within 1 h at the same pulse power density allows increasing the depth of chromium ion alloying from 1.5 to more than 7 μm. The use of ultrafast cooling of the Zr1%Nb alloy surface offers a grain size reduction from a few μm to approximately 50–250 nm, without any microstructural changes throughout the sample volume. An inhomogeneous chromium ion distribution over the target surface and depth is observed.

Electric field driven focusing and transport of plasma ion beams by micro-glass capillaries beyond the self-focusing limit

Micro-glass capillaries emerge as an important tool for the lossless guiding and focusing of ion beams (Kojima 2018 J. Phys. B: At. Mol. Opt. Phys. 51 042001). The self-focusing mechanism of the capillaries is primarily governed by charged patches induced on their inner walls by the incident beam (Stolterfoht et al 2002 Phys. Rev. Lett. 88 133201). However, the dominance of space charge forces over self-focusing forces in intense (J ≈ 1 A m−2) ion beams establishes a self-focusing limit (Maurya et al 2019 J. Phys. D: Appl. Phys. 52 055205), posing challenges to beam focusing beyond this limit. In this work, a novel method is introduced, demonstrating electrical control over the charge patch dynamics through an externally applied bias voltage, thereby enabling the focusing of Ar ion beams beyond the self-focusing limit. Experimental results reveal that adjusting the biasing voltage allows overcoming the self-focusing limit, resulting in the generation of a high-intensity ( Jout≈3.05×105 A m−2) nano-beam (∼160 nm). Furthermore, electrical control is shown to enhance the performance of both straight and tapered capillaries (SC/TC), with the TC being more effective for nano-beam generation. A Particle-In-Cell (PIC) simulation code has been developed to explain the experimental results. The implications of high-intensity nano ion beams in advancing nanopatterning, nanoscale material analysis, and matter wave interferometry, underscore significant contributions to research and innovation within electronics, materials science, nanotechnology, and emerging quantum technologies.

Nuclear structure opportunities with GeV radioactive beams at FAIR.

The Facility for Antiproton and Ion Research (FAIR) is in its final construction stage next to the campus of the Gesellschaft für Schwerionenforschung Helmholtzzentrum for heavy-ion research in Darmstadt, Germany. Once it starts its operation, it will be the main nuclear physics research facility in many basic sciences and their applications in Europe for the coming decades. Owing to the ability of the new fragment separator, Super-FRagment Separator, to produce high-intensity radioactive ion beams in the energy range up to about 2 GeV/nucleon, these can be used in various nuclear reactions. This opens a unique opportunity for various nuclear structure studies across a range of fields and scales: from low-energy physics via the investigation of multi-neutron systems and halos to high-density nuclear matter and the equation of state, following heavy-ion collisions, fission and study of short-range correlations in nuclei and hypernuclei. The newly developed reactions with relativistic radioactive beams (R3B) set up at FAIR would be the most suitable and versatile for such studies. An overview of highlighted physics cases foreseen at R3B is given, along with possible future opportunities, at FAIR. This article is part of the theme issue 'The liminal position of Nuclear Physics: from hadrons to neutron stars'.

Preface

Proceedings of the 20th International Conference on Ion Sources, Victoria, BC, Canada, 2023ICIS’23 was the 20th event in a biennial series of conferences that are dedicated to Ion Sources and their applications, and the first in-person conference of this series after the COVID 19 pandemic. The conference was hosted by TRIUMF (www.triumf.ca), Canada’s Particle Accelerator Centre in Victoria, BC, Canada, September 17 to September 22, 2023. The ICIS series covers the physics and technology of ion sources for scientific research and applications. With the conference being the main event within the ion sources community it offers a forum for exchanging of new ideas and establishing of collaborations.The conference was held at the Victoria Conference Centre in Victoria BC, Canada, with support from the adjacent Fairmont Empress hotel. The venue is located on the traditional, ancestral, and unceded territory of the Lkwungen People, also known as the Songhees and Esquimalt First Nations communities.The biennial conference series covers the physics and technology of ion sources for scientific research and applications. New developments and advancements have been presented and discussed. As in previous conferences of this series, all aspects of ion sources have been covered in the categories:• Fundamental processes in ion sources and plasmas• Production of high intensity ion beams• Production of highly charged ion beams• Negative ion sources• Ion sources for fusion• Radioactive ion sources, charge breeders and polarized beams• Beam formation, extraction, transport, and diagnostics• Applications of ion sources• Key technologies for ion sourcesThe conference was organized in a hybrid mode and a zoom link was made available to participants, who could not attend in person. A total of 178 participants have registered for the conference, of whom 20 were students and 23 attended from remote. Fifty contributions have been presented in plenary sessions of which 20 were invited by the international advisory committee. The remaining 30 have been selected by the Scientific advisory committee. 123 contributions have been presented at 2 poster sessions. The high level and interesting contributions triggered lively discussions during all sessions. Thank you to all who contributed to this.Additional events included a tour of the TRIUMF Laboratory on September 17 just before the conference, and a reception on the same evening. In the afternoon of Wednesday, September 20 delegates were able to enjoy the beautiful surrounding Vancouver Island by either participating in a whale watching tour or a nature hike along the shoreline. In the evening of this day the conference banquet was held in the Fairmont Empress hotel.Fifteen students participated in the student poster competition. Members of both the international advisory committee and the scientific program committee acted as judges. Thank you to all the students who have contributed and the judges. Three winners have been awarded.List of International advisory committee, Scientific program committee, Local organizing committee are available in this pdf.

Application of Optical Emission Spectroscopy to Electron Cyclotron Resonance Ion Sources

Electron Cyclotron Resonance Ion Sources (ECRIS) are widely used for production of highly charged high intensity ion beams for research, medical and industrial applications.ECRIS performances, especially the charge state distribution and beam intensity, depend significantly on the electron energy distribution function that ranges from a few eV to hundreds of keV. Further improvements of ECRIS performances require a deeper and deeper understanding of the plasma heating mechanisms and ion generation by means of opportune plasma diagnostics. Amongst others, optical emission spectroscopy (OES) is the most remarkable for application in ECRIS: it is a non-invasive diagnostics able to operate also in high-voltage conditions and it requires small room for operation. OES has been already tested for plasma diagnostics in proton sources.This work presents the experimental set-up developed for the plasma diagnostics of the Advanced Ion Source for Hadrontherapy (AISHa), an ECRIS for medical applications, together with the strategy applied to relate plasma emission lines in the visible and near-infrared domain to plasma parameters for some ions of interest. Preliminary results and perspectives will be also discussed.

A protype of compact and high-yield DD neutron generator

Neutron generators are widely utilized in various fields, including scientific research, activation analysis, and detection of IED or drugs, due to their high neutron yield, safety, and flexibility. In this paper, we report about the development of a compact and high-yield dd neutron generator based on an Electron Cyclotron Resonance (ECR) ion source at the China Institute of Atomic Energy. The ion source to produce a high-intensity ion beam, which is used to bombard a water-cooled solid metal target. By means of the (D, D) nuclear reaction, 2.5MeV neutrons are generated. We describe the detailed design of this compact dd neutron generator and present the preliminary measurement results of its neutron yield, as measured by a calibrated 3He neutron detector. The generator has been tested for nearly 300 hours, demonstrating stable operation without any component damage. With its compact size, high yield, and long lifespan, this generator could meet the demand for a 2.5MeV neutron source in many scientific research and select industrial applications.

High-Intensity Titanium Ion Implantation into Aluminum under Conditions of Repetitively-Pulsed Energy Impact of a Beam on the Surface

High-Intensity Titanium Ion Implantation into Aluminum under Conditions of Repetitively-Pulsed Energy Impact of a Beam on the Surface

Matched phase sweep method for the optimization of bunching factor in dual rf systems of high-intensity hadron synchrotrons

The scheme of multiturn painting beam injection in a dual harmonic rf system is widely employed in high-intensity proton or heavy ion synchrotrons to alleviate space charge effects. With a momentum offset of the injected beams, a large bunching factor can be achieved at the end of multiturn painting injection process. However, the momentum offset can increase the instantaneous beam peak current during the first 1/4 synchrotron period, causing a reduced bunching factor during the beam injection process. To address this issue, a matched phase sweep method is developed. By matching the synchrotron oscillation frequency and beam injection period, an optimal curve for phase sweeping can be directly obtained. The effectiveness of the method has been checked via simulations and machine study, which are in good agreement. The matched phase sweep method is employed for the increase of the beam power in the upcoming upgrade project of the China Spallation Neutron Source and can also be generally applied for the operation in the presence of dual harmonic rf system in high-intensity hadron synchrotrons. Published by the American Physical Society 2024

Simulation and parameter optimization of 6-dimensional phase space injection scheme based on HIAF-BRing

In high-intensity heavy ion synchrotrons such as HIAF-BRing, mitigating vacuum degradation and consequent beam lifetime reduction caused by injected beam losses remain a key challenge. BRing aims to inject particles on the order of 1011 with a beam loss not exceeding 5% when the collimation system is inactive. This paper introduces a 6-dimensional phase space painting injection (6-D injection) scheme designed to address both the high intensity and low loss challenges. To optimize numerous parameters in the injection schemes, a multi-parameter optimized injection model is constructed. The simulation example without space charge confirms the feasibility of the model, demonstrating the advantage of 6-D injection over multi-turn injection and two-plane painting injection. Subsequent simulations implement multi-parameter optimization under space charge, resulting in a 6-D injection scheme with a beam loss rate of 4%, meeting the desired performance requirements.

Design and Implementation of Chopper Control System for HIAF

The chopper control system which is synchronized by the White Rabbit timing network is designed and implemented to meet the requirements of the chopper of ion source for the High-Intensity Heavy Ion Accelerator Facility (HIAF). The hardware system consists of timing modulation controller, waveform acquisition, parameter setting, and remote control of the chopper power supply. The software includes low-level drivers and top-level applications which are based on Experimental Physics and Industrial Control System (EPICS). The combination of hardware and software completes the interaction of timing messages with the White Rabbit network, waveform acquisition, the setting of timing modulation parameters in several running modes, and remote control of the chopper power supply, etc. The test results show that the system can achieve timing modulation with a resolution of 8 ns and waveform acquisition of embedded EPICS IOC (input/output controller) at a 125 MHz sample rate. The design, implementation, and test of the chopper control system are described in this paper.

Free electron laser prepared high-intensity metastable helium and helium-like ions

In the precision spectroscopy of few-electron atoms, the generation of high-intensity metastable helium atoms and helium-like ions is crucial for implementing experimental studies as well as a critical factor for improving the signal-to-noise ratio of experimental measurements. With the rapid development of free-electron laser (FEL) and technology, FEL wavelengths extend from hard X-rays to soft X-rays and even vacuum ultraviolet bands. Meanwhile, laser pulses with ultra-fast, ultra-intense and high repetition frequencies are realized, thus making it possible for FEL to prepare single-quantum state atoms/ions with high efficiency. In this work, we propose an experimental method for obtaining high-intensity single-quantum state helium atoms and helium-like ions by using FEL. The preparation efficiency can be calculated by solving the master equation of light-atom interaction. Considering the experimental parameters involved in this work, we predict that the efficiencies of preparing metastable 2<sup>3</sup>S He, Li<sup>+</sup> and Be<sup>2+</sup> are about 3%, 6% and 2%, respectively. Compared with the common preparation methods such as gas discharge and electron bombardment, a state-of-the-art laser excitation method can not only increase the preparation efficiency, but also reduce the effects of high-energy stray particles such as electrons, ions, and photons generated during discharge. Furthermore, combined with the laser preparation technique, the sophisticated ion confinement technique, which can ensure a long interaction time between the ions and laser, increases the efficiency of metastable Li<sup>+</sup> and Be<sup>2+</sup> by several orders of magnitude. Therefore, the preparation of high-intensity metastable helium and helium-like ions can improve the measurement accuracy of precision spectroscopy of atoms and ions. A new experimental method, based on FEL, to study the fine structure energy levels 2<sup>3</sup>P of helium, has the potential to obtain the results with an accuracy exceeding the sub-kHz level. Thus, the high-precision fine structure constants can be determined with the development of high-order quantum electrodynamics theory. In order to measure energy levels with higher accuracy, a new detection technique, which can reduce or even avoid more systematic effects, must be developed. For example, the quantum interference effect, which has been proposed in recent years, seriously affects the accuracy of fine-structure energy levels. If the interference phenomenon of spontaneous radiation between different excited states can be avoided in the detection process, the measurement accuracy will not be affected by this quantum interference effect. High-intensity metastable atoms or ions in chemical reaction dynamics studies also have better chances to investigate reaction mechanisms. In summary, the FEL preparation of high-intensity metastable helium atoms and helium-like ions proposed in this work will lay an important foundation for developing cold atom physics and chemical reaction dynamics.

Observation of Beam Emittance Reduction due to Gas Sheet Injection for Beam Profile Measurement

In a high intensity ion accelerator, a non-destructive beam monitor is required to realize a continuous measurement of the beam for improving the beam quality in operation for users. We have developed a non-destructive 2-D beam profile monitor detecting photons produced by interaction between a beam and a sheet-shaped gas. Though the developed monitor is a non-destructive type, the injected gas sheet should induce scattering of the beam particles which makes the beam emittance large. We have measured a beam current and a phase space distribution of the J-PARC 3 MeV, 60 mA H− beam with change of the gas sheet flux. It was found that the beam current reduction was in linear relation and the root mean square emittance was constant or decreased by up to 4.5% in y-y′ plane and did not change in x-x′ plane against a rise in the gas sheet flux. These result indicate that the developed monitor can be utilized as a non-destructive one depending on the gas sheet flux condition.

Preparation and surface nanostructural characterization of multi-emitter sources based on superionic conductor CsAg4Br3-xI2+x (x=0.25)

Since the fabrication of micro-/nano-electronic devices is approaching nanoscales and demanding low energy, high dose ion beam processing with controlled area and dense patterns to meet the current semiconductor industry demands, continuous advancement is needed in terms of material design and ion beam techniques. In this perspective, development of new ion sources may provide advanced technologies useful in the manufacture of high-performance devices. Silver ion beams have salient features including simple generating process, nanoscale beam spot size and high intensity ion current. In this paper, we have developed a solid electrolyte multi emitter ion source (SEIS) with CsAg4Br3-xI2+x (x = 0.25) films deposited on silver tips. Ag+ ion emission is significantly enhanced with the added number of emitters and the ion current of 1.95 μA (with four emitter tips) has been obtained at 168 °C temperature and 20 kV accelerating voltage. The stability and cooling/heating curves of the multi-emitter ion beam are measured, and the interrelation between ion current intensity and mechanism of shape geometry of the emitter tips are discussed. Finally, both the solid electrolyte multi-tip emitters and the collector surfaces are analyzed, with an attempt to precisely control of formation of the nanoparticles (NPs) including their size and height through the control of the ion implantation parameters.

Ion-optical updates and performance analysis of High energy FRagment Separator (HFRS) at HIAF

The High energy FRagment Separator (HFRS), a new generation in-flight radioactive separator, is under construction at the high-intensity Heavy Ion Accelerator Facility (HIAF) in China. To further optimize the separator performance and consider the manufacturing technology, the specifications of some magnetic elements of the HFRS separator have been modified from the original design reported earlier, and prototypes of partial magnetic elements have been fabricated and tested. In this paper, updates of magnetic parameters, test results of prototypes, and development of ion-optical calculation are presented. The high-order correction of aberrations is demonstrated. The performance of the separator is studied using fission reactions and fragmentation reactions of relativistic 238U projectiles. This work will guide the forthcoming experiments in the future HFRS separator.

Features of titanium ion beams formation taking into account ion-electron emission realizing the synergy of high-intensity ion implantation and pulsed energy impact on the surface

In this work, we show the possibility of forming titanium ion beams of submillisecond durationin the average ion energy range from 20 to 60 keV with a maximum ion current densityof 3.3 A/cm2 at a pulsed power density of 132 kW/cm2 in individual pulses. The dependence of theion-electron emission coefficient on the average energy and current of the arc discharge is presented.It has been established that the ion-electron emission coefficient in the case of irradiation of a stainlesssteel target with a beam of titanium ions reaches a value of 1.6 at an average ion energy of 60 keV.The dependences of the radial distribution of the ion current density on the average ion energy areobtained for different positions of the collector relative to the geometric focus of the ballistic systemfor focusing the ion beam. Taking into account ion-electron emission, it has been experimentallyshown that with an increase in the average ion energy from 20 keV to 40 keV, an increase in the densityof the measured ion current is observed, while in the range from 40 to 60 keV, the ion current densitydecreases. Using nineteen collector sensors, it was shown that due to the influence of the partiallyuncompensated space charge of the ion beam, the best conditions for its focusing are achieved at adistance of 20 mm behind the geometric focus of the system.

Study of the synergy effect of high-intensity aluminum ions implantation into titanium and energy impact on the surface

The work studies the synergy effect of high-intensity implantation of aluminum ions and thesubsequent impact of a powerful pulsed ion beam on the microstructure and properties of titanium.Specimens of titanium were implanted for one hour at a temperature of 1170 K with an ion fluenceof 1021 ions/cm2. Layers with a thickness of about 150 μm were obtained. The energy impact wascarried out by a powerful nanosecond pulsed ion beam with an ion current density on the targetof 100 A/cm2. The paper presents data on changes in the elemental composition, surface morphology,and microstructure of ion-doped and energy-modified layers. It has been established that the additionalenergy impact on the ion-doped layer of a powerful pulsed beam improves microstructure at depthsgreater than 3.4 μm. The synergistic of high-intensity ion implantation of aluminum and the energyimpact of a pulsed ion beam improves the wear resistance of titanium by eighteen folds.