Metal Ion Beams Research Articles

Transient Superhydrophilic Surface Modification of Polyimide by Metal Ion Beam Irradiation.

Polyimide is commonly used as a substrate for flexible electronic devices because of its excellent thermal, physical, and electrical properties. To enhance the adhesion between substrates and electrodes, it is necessary to improve the hydrophilic properties of the polyimide. Various surface treatments, such as plasma treatment, laser ablation, and ultraviolet treatments, have been applied for this purpose. In this study, we demonstrated that Cu and Ti ion beam irradiation can temporarily create a superhydrophilic surface on polyimide after irradiation. When Cu or Ti ions bombarded the polyimide, the contact angle changed systematically with the beam current density and over time. We present atomic force microscopy (AFM) data for polyimide irradiated with Cu and Ti ions at different beam current densities and discuss the possible mechanisms behind the changes in the contact angle.

Research and development activities to increase the performance of the CAPRICE ECRIS at GSI

At GSI the CAPRICE ECRIS is in operation to deliver high charge state ion beams from gaseous and metallic elements to the accelerator facility. A test campaign has been carried out at the ECR test bench to fulfill the demand for higher intensity and stability of high charge state ions and for mixed ion beams. The ion beam stability has been monitored by an Optical Emission Spectrometer (OES), which has been already used to check the plasma and the temperature of the resistively heated oven during metal ion beam operation, particularly for Ca ion beams. During the test campaign, it was investigated that the OES can be used for monitoring the stability of ion beams from gaseous elements and mixed ion beams, and the main achieved results are reported. The ion beams extracted from the ECRIS have been simulated with a particle tracking code in order to study and improve the beam matching into the RFQ. The preliminary results of the study together with possible modifications of the extraction column are presented.

ASTERICS, a new 28 GHz electron cyclotron resonance ion source for the SPIRAL2 accelerator

A new A/Q=7 injector is under development for the SPIRAL2 accelerator at Caen, France (NEWGAIN project). A new 28 GHz superconducting electron cyclotron resonance ion source named ASTERICS is under design for this project. The source features a modern cryostat and a large plasma chamber (91 mm radius and 600 mm length). The physical and technical motivations for a larger plasma volume are detailed and estimates of expected beam intensities enhancement are discussed. The source will mainly produce metallic ion beams: the concept of a temperature-controlled liner (up to 900°C) to stabilize high vapor pressure metal re-evaporation in the source is presented. The preliminary design of the ion source and its superconducting magnet are described.

Metal evaporation dynamics in electron cyclotron resonance ion sources: plasma role in the atom diffusion, ionisation, and transport

We present a numerical study of metals dynamics evaporated through resistively heated ovens in electron cyclotron resonance (ECR) plasma traps, used as metal ion beam injectors for accelerators and multi-disciplinary research in plasma physics. We use complementary numerical methods to perform calculations in the framework of the PANDORA trap. The diffusion and deposition of metal vapours at the plasma chamber’s surface are explored under molecular flow regime, with stationary and time-dependent particle fluid calculations via COMSOL Multiphysics®. The ionisation of vapours is then studied in the strongly energised ECR plasma. We have developed a Monte Carlo (MC) code to simulate the in-plasma metal ions’ dynamics, coupled to particle-in-cell simulations of the plasma physics in the trap. The presence of strongly inhomogeneous plasmas leads to charge-exchange and electron-impact ionisations of metals, in turn affecting the deposition rate/pattern of the metal on the walls of the trap. Results show how vapours dynamics depends both on evaporated metals and the plasma target. The 134Cs, 176Lu, and 48Ca isotopes were investigated, the first two being radioisotopes interesting for the PANDORA project, and the third as one of the most required rare isotope by the nuclear physics community. We present an application of the study: MC computing the γ activity due to the deposited radioactive neutral nuclei during the measurement time, we quantitatively estimated the overall γ-detection system’s efficiency using GEANT4, including the poisoning γ-signal from the walls of the trap, relevant for the γ-tagging of short-lived nuclei’s decay rate in the PANDORA experiment. This work can give valuable support both to the evaporation technique and plasma source optimisation, for improving the metal ion beam production, avoiding huge deposit/waste of metals known to affect the long-term source stability, as well as for radio-safety aspects and reducing material waste in case of rare isotopes.

Features of the formation and diagnostics of powerful metal ion beams with submillisecond duration

The article presents the results of experimental studies on the formation of repetitively-pulsed beams of titanium ions with submillisecond pulse duration from the continuous vacuum arc discharge plasma. The influence of ion-electron emission on the overestimation of the measured ion current with a power density of tens and hundreds of kilowatts per square centimeter was studied using various methods. It has been established that at an average energy of titanium ions of about 80 keV, due to ion-electron emission, the measured current is three times higher than the real ion beam current. Complicating the measurement of the current and energy parameters of the ion beam, the ion-electron emission ensures the neutralization of its space charge during the entire duration of the pulse. An increase in the ion current density due to ballistic focusing to more than 1 A/cm2 does not change the ion-electron emission coefficient. It is shown that, as a result of incomplete ion beam space charge neutralization, its crossover is shifted by 20 mm beyond the geometric focus of the system. The possibility of forming submillisecond high-intensity titanium ion beams with a current density exceeding 2.8 A/cm2, a power density exceeding 200 kW/cm2, and a pulse energy exceeding 100 J has been experimentally demonstrated. Data are obtained on the change in the current density over the ion beam cross-section depending on the accelerating voltage amplitude, the vacuum arc discharge current, and the distance from the focusing electrode.

Ion Beam as an External and Dynamic Metal Reservoir to Induce Nanoparticle Exsolution in Oxides

A central theme in solid oxide fuel cells (SOFC) and electrolyzers (SOEC) is to design stable and catalytically active solid/gas interfaces toward desired reactions. A recent advance in this regard is to synthesize nanoparticles decorated electrodes in a process termed “exsolution”. Exsolution generates stable and catalytically active metal nanoparticles via phase precipitation out of a host oxide. Unlike traditional nanoparticle infiltration techniques, the nanoparticle catalysts from exsolution are anchored in the parent oxide. This strong metal-oxide interaction makes the exsolved nanoparticles more resistant against particle agglomeration as compared to the infiltrated ones. In addition, the exsolved particles also open up the possibility of regeneration of catalysts. To date, the concept of exsolution has been successfully applied to a number of applications including SOFC/SOEC, ceramic membrane reactors, chemical looping combustion, and (electro)catalysis.As the exsolution process starts with a solid-solution that contains the to-be-exsolved transition metal ions, this method is often limited by the intrinsic solubility limit of the host oxide. Here, we propose that ion beam irradiation to be a unique tool to promote exsolution as it can introduce defects and dopants into the host oxides and at concentrations higher than thermodynamic limits. Moreover, due to the surface sputtering effect, ion beam irradiation can modulate the surface morphology, creating novel nanostructures.To demonstrate this approach, we chose thin-film perovskite SrTi0.65Fe0.35O3 (STF) and fluorite Ce0.5Zr0.5O2 (CZO) as model systems, both of which are promising materials in SOFC and SOEC. We modulated metal exsolution in both materials with in-situ 10-150 keV Ni irradiation at 800 °C in vacuum. Ni irradiation on STF controllably changed the exsolved particle composition from unitary Fe to bimetallic Fe-Ni. Moreover, it also reduced the particle size down to sub-2 nm, which outperforms other tuning methods thus far in the literature. As a result, the irradiation-modified STF demonstrated superior catalytic activity toward room-temperature oxygen evolution reactions (OER) than the conventional thermally exsolved STF. Regarding CZO, Ni irradiation also decorated the surface with well-dispersed nanoparticles, leading to enhanced high-temperature H2O splitting kinetics. The effective size and composition control over exsolution highlights the utility of metal ion beams in promoting and tailoring exsolved nanocatalysts for a broad range of applications in clean energy and fuel conversion. Figure 1

A compact dication source for Ba2+ tagging and heavy metal ion sensor development

We present a tunable metal ion beam that delivers controllable ion currents in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed by sequential atomic evaporation and single or multiple electron impact ionization, followed by acceleration into a sensing region. Controllability of the ionic charge state is achieved through tuning of electrode potentials that influence the retention time in the ionization region. Barium, lead, and cadmium samples have been used to test the system, with ion currents identified and quantified using a quadrupole mass analyzer. Realization of a clean Ba2+ ion beam within a bench-top system represents an important technical advance toward the development and characterization of barium tagging systems for neutrinoless double beta decay searches in xenon gas. This system also provides a testbed for investigation of novel ion sensing methodologies for environmental assay applications, with dication beams of Pb2+ and Cd2+ also demonstrated for this purpose.

Neutralization of the Surface Charge of an Insulated Target under the Interaction of High-Energy Metal Ion Beams

The interaction of ion beams with dielectric materials is an urgent problem, both from the point of view of practical application in ion implantation processes and for understanding the fundamental processes of charge compensation and the effective interaction of beam ions with a target surface. This paper presents the results of studies of the processes of compensation of the surface charge of an insulated collector upon interaction with a beam of metal ions with energies up to 50–150 keV. At low pressure (about 10−6 torr), removing the collector from the region of extraction and beam formation makes it possible to reduce the floating potential to a value of 5–10% of the total accelerating voltage. This phenomenon allows for the efficient implantation of metal ions onto the surface of alumina ceramics. We have shown that the sheet resistance of dielectric targets depends on the material of the implanted metal ions and decreases with an increase in the implantation dose by 3–4 orders of magnitude compared with the initial value at the level of 1012 Ω per square.

Simulation and experimental studies on the formation of high-power titanium ion beams for the synergy of ion implantation and energy impact on the surface

The development of a material modification method based on synergy of high-intensity ion implantation and simultaneous energy impact on the surface is aimed at creating deep ion-doped layers. To implement this method, the high power density of pulsed and repetitively-pulsed beams of metal and gas ions with micro-submillisecond duration are required. The paper presents the results of numerical simulation and experimental studies on the formation of pulsed high-intensity metal ion beams from vacuum arc plasma. The ballistic focusing of heavy ions at injection currents from 0.1 to 1 A has been studied. The influence of the ion current density, accelerating voltage, and conditions for neutralizing the beam space charge on the transport and focusing of a high power density ion beam has been studied. The possibility of ballistic formation of submillisecond titanium ion beams with a pulse power density of a hundred kilowatts per square centimeter has been experimentally shown.

Charge breeder of Electron Cyclotron Resonance type: A new application to produce intense metal ion beams for accelerators

Metal ion beams are more and more requested by physicists (Nuclear Physics, Material Physics) for their experiments. At GANIL, they are produced by Electron Cyclotron Resonance (ECR) Ion Sources for the two accelerator machines: ECR4 & ECR4M (Sortais et al., 1989) [1] for the Cyclotrons and PhoenixV3 for the Linac (Thuillier et al., 2016) [2]. One of the challenges is to produce these beams with high global efficiency: today, total ionization efficiency varies between ∼1% and ∼28% regarding the method carried out. A new alternative would be the 1＋/N＋ method studied intensively for the past twenty years in the framework of Radioactive Ion Beam (RIB) production. In this article, the primary results leading to the proof of principle of that technique applied to the production of metal ion beams is presented.

Development of a new generation of ion beams

Ion beams have many applications. Junior Associate Professor Masahi Nojima, Research Institute of Science and Technology at the Tokyo University of Science, Japan, is working to create a new generation of ion beams. Already, he has successfully developed new techniques for producing focused ion beams (FIB). In his most recent work, Nojima has developed a metallic solution ion source that will be used to construct unknown functional materials by using ion beams made up of specific elements. The metallic solution ion source can generate a copy of an original structure using elementally selected materials. With support from the Japan Society for the Promotion of Science (JSPS), KAKENHI, the academic incentive system of the KIOXIA Corporation 2021 and the Toshiba Electric Devices & Storage Corporation 2021, Nojima is seeking to open up new materials for use as ion sources utilising electrospray ionisation (ESI) methods. By harnessing the elements of FIBs primarily created from liquid metal ion source (LMIS) by field ionisation processes, Nojima hopes to create new generations of ion beams. To date, he and the team have displayed the result of mass separating metallic ion solution ion beams on random conditions and, looking ahead, intend to estimate the stopping range of mass selected ion beams in solid materials.

Mn2+ doping inside glass substrate utilizing metal ion beam implantation technique

The Korea multi-purpose accelerator complex (KOMAC) has been providing metal ion beam services such as Cr+, Fe+, Co+, Cu+, Mg+ and Ni+ using a modified Bernas ion source for diverse users. In this study, metal ion implantation facilitated by KOMAC has been utilized to implant Mn+ ions into a glass substrate. First, phosphate glass substrate doped with CeBr3 was fabricated following melt-quenching technique and then Mn+ ion beam was irradiated with flounces of 5 × 1016 ions/cm2. The irradiated sample was heat-treated at 400 °C, and characterized by absorption, excitation, and emission spectra. The presence of Mn2+ and the existence of energy transfer from Ce3+ to Mn2+ were explored by characteristic emission and excitation spectra. The emission intensity of Mn2+ was significantly higher when excited by Ce3+ excitation than Mn2+.

A few ECRIS developments at LBNL

In addition to the ongoing investigation of bremsstrahlung radiation produced by energetic electrons in the superconducting Electron Cyclotron Resonance (ECR) ion source VENUS, the LBNL ion source group has pursued several other research topics since 2015 to explore potential advancements of ECR ion sources. Three of these activities are investigations into the benefits of non-cylindrical plasma chambers, the development of new high-temperature ovens that will efficiently produce the intense, metallic ion beams necessary for super heavy element production at the 88-Inch Cyclotron facility, and the finalization of the conceptual and engineering design of the superconducting NbTi magnet structure for the 4th generation, 45 GHz ECR ion source MARS-D. This article summarizes and briefly discusses the highlights of these ECRIS developments.

Development of a new generation of ion beams

Ion beams have many applications. Junior Associate Professor Masahi Nojima, Research Institute of Science and Technology at the Tokyo University of Science, Japan, is working to create a new generation of ion beams. Already, he has successfully developed new techniques for producing focused ion beams (FIB). In his most recent work, Nojima has developed a metallic solution ion source that will be used to construct unknown functional materials by using ion beams made up of specific elements. The metallic solution ion source can generate a copy of an original structure using elementally selected materials. With support from the Japan Society for the Promotion of Science (JSPS), KAKENHI, the academic incentive system of the KIOXIA Corporation 2021 and the Toshiba Electric Devices & Storage Corporation 2021, Nojima is seeking to open up new materials for use as ion sources utilising electrospray ionisation (ESI) methods. By harnessing the elements of FIBs primarily created from liquid metal ion source (LMIS) by field ionisation processes, Nojima hopes to create new generations of ion beams. To date, he and the team have displayed the result of mass separating metallic ion solution ion beams on random conditions and, looking ahead, intend to estimate the stopping range of mass selected ion beams in solid materials.

Metal evaporation study using the GANIL high temperature oven for intense metal ion beams production

A new resistive oven dedicated to the production of metal ion beams using ECR ion sources has been developed at GANIL. It aims to produce beams such as 58Niq+, 50Tiq+, 50Vq+ or 238Uq+ with ECR4 ion source on cyclotrons injectors and with Phoenix V3 ion source on Spiral 2facility. Typical intensity about 1.2 1013 pps is requested for the Super Separator Spectrometer (S3). Evaporated atom fluxes and their angular distributions have been measured on a dedicated test bench thanks to a quartz microbalance. These investigations were carried out using three crucibles with various exit caps geometries for which the fluxes and angular distributions display distinct behaviors. Based on those results, crucible is designed to obtain a high flux of atoms overlapping the ECR plasma while minimizing the atoms losses on the ion source chamber.

The AISHa ion source at INFN-LNS

The Advanced Ion Source for Hadrontherapy (AISHa) is an ECR ion source operating at 18 GHz, developed with the aim of producing high intensity and low emittance highly charged ion beams for hadrontherapy purposes. Due to its unique peculiarities, AISHa is a suitable choice for industrial and scientific applications. In the framework of the INSpIRIT and IRPT projects, in collaboration with Centro Nazionale di Adroterapia Oncologica (CNAO), new candidates for cancer treatment (including metal ion beams) are being developed. Moreover, within the IONS experiment, AISHa will be the test-bench for the development of an innovative active plasma chamber designed to increase plasma confinement by changing plasma fluxes. OES technique will be also used to refine techniques of non-invasive plasma diagnostics. Finally, a dedicated setup is under realization to provide impinging beams and detection systems for target production in nuclear physics experiments.

Ga-ion beam surface modification of glass using a custom-built liquid metal ion beam

The application of a Ga-liquid metal ion beam (Ga-LMIB) for surface modification is reported. Ga-LMIB treatment on the glass surface resulted in the implantation of Ga ions and the formation of sub-micrometer mounds. The glass surface hydrophobicity was also found to be enhanced as a result of the Ga-LMIB treatment; additionally, a photocatalytic activity that promoted organic dye decomposition was observed. Ga-LMIB application can be considered to be a new surface modification strategy for the construction of locally hydrophobic and photocatalytic surfaces.

Формирование мощных импульсных пучков ионов титана субмиллисекундной длительности из плазмы вакуумной дуги

The development of a method to improve performance properties of various materials, based on the synergy of high-intensity ion implantation and simultaneous energy impact on the surface, is aimed at creating deep ion-doped layers. Repetitively-pulsed high-power density beams of metal and gas ions with submillisecond duration are required to implement this method. This article presents the results of experimental studies on the forming pulsed high-intensity titanium ion beams from vacuum arc plasma. The effect on focusing and transport efficiency of the cell sizes of the grid focusing electrode in the form of a part of a sphere has been studied. The possibility of ballistic focusing of a titanium ion beam with a pulse duration from 150 to 500 μs with a power density of up to 100 kW/cm2 has been experimentally shown.

Generation of high-power submillisecond metal ion beams

The possibility of using one grid electrode in the form of a part of a sphere for extraction from a free plasma boundary and focusing of metal ions is shown for the first time using titanium ions as an example to form a pulsed beam with a duration of 500 μs and a power density reaching 105 W/cm2. The results of studying the influence of the amplitude of the accelerating voltage in the range of 9-30 kV and the size of the grid cells on the efficiency of space charge neutralization and ion beam focusing are presented. Keywords: metal ions, vacuum arc plasma, submillisecond beams, high power density.

Features of the Formation of Ultralow Energy High-Intensity Metal and Gaseous Ion Beams

This article studies the features and patterns of the formation of high-intensity beams of metal and gaseous ions of low and ultralow energy from dc vacuum arc and gas-discharge plasma. It presents the results of repetitively pulsed plasma immersion extraction of aluminum, titanium, and nitrogen ions from the plasma followed by the formation and transport of ion beam under conditions of its ballistic focusing. This article presents the experimental data on the influence of the grid focusing electrode cell sizes of 150 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$500~\mu \text{m}$ </tex-math></inline-formula> , the bias potential amplitude from 0.1 to 2 kV, the conditions for neutralizing the space charge of the beam during preliminary plasma injection into drift space and when using an additional thermoelectron source on the transport and focusing of ion beams. Here, it discusses the effect of the characteristic dimensions of the fine-structured grid and plasma parameters at ultralow bias potential amplitudes and the presence of significant initial energy in ions on the ion beam focusing. It was found that at bias potential amplitudes of 0.6 kV, it is possible to form repetitively pulsed ion beams with high current density reaching 170 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The obtaining of such beams opens up the possibility of implementing the method of high-intensity ion implantation under conditions of multiple decreases in the irradiated surface sputtering.