Type Ion Source Research Articles

System for Measuring Emittance Characteristics of Ion Sources

The article presents the results of the development of a system for measuring emittance characteristics of ion sources studied at the IAP NAS of Ukraine with the aim of obtaining the ion beams with a high brightness. The emittance measurement system is based on the scheme of an electrostatic scanner and consists of two main parts: the scanner, which moves in the direction perpendicular to the beam axis using a stepper motor, and the electronic system of control, processing and data acquisition. The electronic system contains a Raspberry pi 3B microcomputer, precision DAC/ADCs, the high-voltage amplifier of a scanning voltage up to ±500 V on deflection plates of the scanner and a wide range current integrator. The determination of the emittance consists in measuring the ion beam intensity distribution when the scanner moves along the x-coordinate and the electrostatic scanning along the x´ angle. The obtained two-dimensional data array allows determining the main characteristics of ion beam: geometric 90% emittance, the root mean square (rms) emittance, the Twiss parameters and phase ellipse of rms emittance, the beam current profile and the angle current density distribution. To test the performance and functionality of the system, the emittance characteristics of the penning type ion source were measured. The working gas was helium, and the beam energy varied within 7–15 keV. At 13 keV of beam energy the following emittances of the He+ ions beam was obtained: 90% emittance is 30 π∙mm∙mrad, rms emittance is 8.4 mm∙mrad, and the normalized rms emittance is equal to 0.022 mm∙mrad. The developed system for measuring the emittance of the ion beams is characterized by a short measurement time of 10-15 minutes.

Exploring sample size limits of AMS gas Ion Source 14C analysis at Cologneams

ABSTRACTIncreasing demands for small-scale radiocarbon (14C) analyses required the installation of a “SO-110 B” type ion source (HVE Europa B.V.) at our 6 MV Tandetron AMS (HVE) dedicated for the direct injection of CO2 using either the gas injection system (GIS) from Ionplus AG or a EuroVector EA 3000 elemental analyzer (EA). We tested both systems with multiple series of 14C-free and modern standards (2.5–50 µg C) combusted in quartz ampoules or EA containers and were able to quantify exogenous C introduced. In EA-GIS-AMS analysis exogenous C is mainly derived from the EA sample containers. Blank values for 50 µg C combusted in solvent-cleaned tin (Sn) vessels were 0.0127 ± 0.0012 F14C (boats) and 0.0090 ± 0.0010 F14C (capsules), while they were much higher for thermally cleaned silver (Ag) capsules. The processing of gas samples for GIS-AMS yields similar blank values corresponding to 0.30 ± 0.08 µg exogenous C with 0.93 ± 0.23 F14C consisting of 0.28 µg C modern and 0.02 µg C fossil C. The combustion of larger amounts of blank material (1 mg C) in a single quartz tube split into aliquots gives lower blanks (0.0064 ± 0.0008 F14C; 50 µg C). Thus, 14C analysis of small, gaseous samples is now possible at CologneAMS.

Field-Map And Beam Transport Calculations of The Magnetic Separator At Alto Facility At Orsay

The Institute of Nuclear Physics at Orsay (IPNO) has always been a major player in building accelerators for nuclear physics. The Accelerator Linear Tandem Orsay (ALTO) facility is powered by a 50 MeV/10uA linear electron accelerator dedicated to the production of radioactive beams [1]. The production mode is based on the photo-fission process of a thick UCx target heated up to 2000°C and using the Isotopes Separation On-Line (ISOL) technique [2]. For the ionization of the released fission fragments, three ion source types can be coupled to the target: a Febiad ion source, surface ion source, and laser ion source. The facility can deliver the radioactive ions beams (RIB) to six different experimental setups. The mass of the produced mono-charged Radioactive Ions Beam is selected using a magnetic dipole in order to select a nucleus before its transmission through electrostatic devices up to the experimental setups [3]. This paper is focused on the separator that was built and exploited with success since 43 years. The separator is located closely to the exit of the source of RIB production. We propose to revisit this dipole with a precise field-map calculation and particles transport simulations. These results will be used as a first brick for the understanding and reliability of the transmission along the RIB lines at the ALTO facility.

Simultaneous profiling of vitamin D metabolites in serum by supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS)

Simultaneous profiling of serum vitamin D (VD) metabolites with similar structures is a big challenge. Thus, we developed and validated a SFC-MS/MS method, which is capable of eluting hydrophobic molecules, for quantification of VD2/VD3, 25-OH VD2/VD3, 3-epi-25-OH VD2/VD3, 1,25-(OH)2 VD2/VD3 and 24,25-(OH)2 VD2/VD3. VD metabolites were extracted from human serum using acetonitrile solvent. Column stationary phase, elution gradients, flow rate, column temperature, ion-source type and buffer system in post-column make-up solvent were optimized. Baseline separation of 10 VD metabolites can be achieved using PFP column within 10 min; and detection performed under positive electrospray ionization mode allowed quantification of VD metabolites in serum matrix with a limit of quantification (LOQ) varrying from 0.071 to 0.704 ng/mL. The accuracy was controlled with relative bias lower than 5.5% for QC and NIST samples. The developed method showed excellent intra-assay (0.52–7.93% RSD) and inter-assay (1.35–9.04% RSD) precision. The methodology shows enhanced efficiency and sensitivity as compared to LC-MS/MS method using the same column and mass spectrometer, along with significant correlation and low mean difference bias on measurements. For analysis of trace 1,25-(OH)2 VD2 and 1,25-(OH)2 VD3 in normal human serum or plasma, further improvement of LOQ (like derivatization) should be considered. In conclusion, the use of supercritical fluid not only enhanced safety with reduced solvent cost, but also improved retention and sensitivity as compared to LC-MS/MS method. The developed SFC-MS/MS method is appropriate for high throughput analysis of multiple VD metabolites in human serum with reduced solvent and economic cost.

The increasing of H−current from Penning ion source with electrically biased metal hydride cathode

The possibility of the current increasing of negative hydrogen ions H− extracted in the longitudinal direction from gas-feed-free Penning type ion source with metal hydride cathode by the electric cathodes bias has been investigated. The separation of negative ions from the extracted flux of charged particles was performed by an electromagnetic filter, which consists of a magnetic coil for electron diverting and a grid under positive potential for positive ion reflection. The optimum for the effective extraction of H− ions has been determined. The H− ion current of 10 μA was obtained at an input power of 6 W.

Simulation and optimization of a negative hydrogen Penning ion source

The results of a Particle-In-Cell Monte-Carlo Collision simulation of a cold cathode Penning type ion source are presented. The source is designed to generate H− ions through the volume production process. Twenty-one important processes including electron and heavy particle collisions are introduced into the simulation. The main focus was the energy distribution of electrons which has a large effect on the H− production rate in the volume production. The dependence of the energy distribution of electrons on the axial magnetic field was investigated. The large sensitivity of the H− production rate to the energy distribution of electrons was measured. It was observed that for an anode with a 5 mm radius increasing the axial magnetic field in the range of 0.5–1.1 T results in the increase in the H− density almost by a factor of 14. In addition, it was found that the anode with a radius of 5 mm was the most efficient anode in H− production among the anodes with radii from 3 to 6 mm.

SIESTA: A high current ion source for erosion and retention studies.

Second ion experiment for sputtering and TDS analysis is a high-current ion source for erosion and retention studies with focus on wall materials for fusion devices. The system is composed of a DuoPIGatron type ion source, three consecutive grids for ion extraction, acceleration and beam focusing, a differential pumping stage, a dipole magnet for mass filtering, a quadrupole doublet lens, a target chamber, a load-lock, and a chamber for thermal desorption spectrometry. The acceleration potential of the source can be varied between 500 V and 10 kV. The target chamber has a base pressure of 10-8 mbar and an operating pressure of 5 × 10-7 mbar. The target can be rotated to study angle-dependent effects and can be heated via electron-impact heating up to 1300 K for high temperature erosion and implantation studies. The target chamber is equipped with an in situ magnetic suspension balance. The operating parameters of the ion source were mapped to achieve the maximum ion current at the target for various gas species and accelerating potentials. The beam emittance for a D3 + ion beam was measured after deflection in the dipole magnet. This was used for ion beam simulations, which were instrumental for the design of the quadrupole lenses. If the quadrupole doublet is used, the ion flux to the target is increased by up to a factor of 4. Additionally, the relative population of neutral particles present in the beam at the target was quantified and is equal to 0.8% when averaged over the measurement positions. The typical beam footprint at the target under normal incidence has an area of 0.5 cm2. The ion current reaching the target increases with the accelerating potential. Due to this effect, the ion flux density at the target in the low-ion-impact-energy range can be increased by operating the source at a higher extraction potential and by applying a (decelerating) potential to the target. Ion impact energies as low as 200 eV/D are achieved this way with a D3 + current of 100 μA when focusing the beam with the quadrupole doublet lens, equating to a D particle flux density of 3.7 × 1019 m-2 s-1. At ion impact energies of 2 keV/D, the maximum achievable flux density with D3 + is 6 × 1019 D m-2 s-1. Experimental determination of sputter yields was performed via ex situ weight loss measurement for bulk Au samples, showing reasonably good agreement with simulations and experimental data from the literature.

Etching of glass, silicon, and silicon dioxide using negative ionic liquid ion sources

Ionic liquid ion sources have been proposed as a new type of ion source for focused ion beam and broad ion beam applications. In this paper, the ionic liquid EMI-BF4 (1-ethyl-3-methylimidazolium tetrafluoroborate) was used as an ion source to generate negatively charged ions and irradiate glass (Pyrex 7740), silicon, and silicon dioxide targets. The results indicate that negative EMI-BF4 ion beams can prevent issues related to surface charge accumulation on dielectric substrates, achieving etching selectivities of SiO2:Si of at least 1.55. The etching rate increases on glass, silicon, and silicon dioxide at higher ion landing energies. It is shown that the negative EMI-BF4 beam has a higher yield than traditional metal gallium ion beams, likely due to the chemical reactivity of fluorine radicals. This effect is also noticeable when compared to results using positive EMI-BF4 beams.

Invited Review Article: Modeling ion beam extraction from different types of ion sources

The applications of ion beams are manifold. In most systems, improved extraction of the ion beam from the ion source can help to increase the ion beam current or to improve the ion beam emittance. Real understanding of the complete system is required to achieve improvement of ion beam intensity or ion beam quality. Mathematically, the situation is described by a boundary value problem for the fields and an initial value problem for ion beam tracking. Whereas the boundary value problem is similar for different ion sources, the initial value problem to be solved depends on very specific ion source conditions. The influence of different parameters like particle density and temperatures on the discharge itself is important. For the case of ion beam extraction from an electron cyclotron resonance ion source, the problems of a suitable model will be discussed in detail. It will be shown that specific diagnostics are required to measure specific beam parameters. Such diagnostics are to be included in the simulation as well. The overall goal remains to develop a model that can be used for further improvements of beam intensity and quality from specific ion sources.

ULTRA-LOW INTENSITY PROTON BEAMS FOR RADIATION RESPONSE RELATED EXPERIMENTS AT THE U-120M CYCLOTRON

The U-120M cyclotron at the Nuclear Physics Institute (NPI) of the Czech Academy of Sciences in Rez is used for radiation hardness tests of electronics for high-energy physics experiments. These tests are usually carried out with proton fluxes of the order of 10<sup>5</sup>–10<sup>9</sup> proton·cm<sup>−2</sup>·s<sup>−1</sup>. Some tests done for the upgrade of the Inner Tracking System of the ALICE experiment at CERN, however, required proton beam intensities several orders of magnitude lower. This paper presents a method which has been developed to achieve the proton beam flux of the order of 1 proton · cm<sup>−2</sup>·s<sup>−1</sup>. The method is mainly based on reduction of the discharge current in the cyclotron internal Penning type ion source. Influence of this new operation mode on the lifetime of ion source cathodes is discussed.

The requirements for low-temperature plasma ionization support miniaturization of the ion source.

Ambient ionization mass spectrometry (AI-MS), the ionization of samples under ambient conditions, enables fast and simple analysis of samples without or with little sample preparation. Due to their simple construction and low resource consumption, plasma-based ionization methods in particular are considered ideal for use in mobile analytical devices. However, systematic investigations that have attempted to identify the optimal configuration of a plasma source to achieve the sensitive detection of target molecules are still rare. We therefore used a low-temperature plasma ionization (LTPI) source based on dielectric barrier discharge with helium employed as the process gas to identify the factors that most strongly influence the signal intensity in the mass spectrometry of species formed by plasma ionization. In this study, we investigated several construction-related parameters of the plasma source and found that a low wall thickness of the dielectric, a small outlet spacing, and a short distance between the plasma source and the MS inlet are needed to achieve optimal signal intensity with a process-gas flow rate of as little as 10mL/min. In conclusion, this type of ion source is especially well suited for downscaling, which is usually required in mobile devices. Our results provide valuable insights into the LTPI mechanism; they reveal the potential to further improve its implementation and standardization for mobile mass spectrometry as well as our understanding of the requirements and selectivity of this technique. Graphical abstract Optimized parameters of a dielectric barrier discharge plasma for ionization in mass spectrometry. The electrode size, shape, and arrangement, the thickness of the dielectric, and distances between the plasma source, sample, and MS inlet are marked in red. The process gas (helium) flow is shown in black.

A 60 mA DC H− multi cusp ion source developed at TRIUMF

This paper describes the latest high-current multi cusp type ion source developed at TRIUMF, which is capable of producing a negative hydrogen ion beam (H−) of 60 mA of direct current at 140V and 90A arc. The results achieved to date including emittance measurements and filament lifetime issues are presented. The low current version of this ion source is suitable for medical cyclotrons as well as accelerators and the high current version is intended for producing large neutral hydrogen beams for fusion research. The description of the source magnetic configuration, the electron filter profile and the differential pumping techniques given in the paper will allow the building of an arc discharge H− ion source with similar properties.

Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE**This article belongs to the Focus on Exotic Beams at ISOLDE: A Laboratory Portrait special issue.

At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of–the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210–950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser–atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments.

On the beam emittance/brilliance of highly charged ions extracted from the Frankfurt 14GHz Electron-Cyclotron-Resonance-Ion-Source in standard and enhanced (MD) mode

SynopsisElectron Cyclotron Resonance Ion Sources (ECRIS) provide only moderate emittances as compared to other types of ion sources. Besides considerable effort to improve the total output of ECRIS’s by dedicated modifications (gas mixing, wall coating etc.), it is important to also determine the influence of such improvements on the beam quality. In this contribution dedicated experiments on the influence of the MD method [1] on the emittance/brilliance of extracted ion beams from the Frankfurt 14GHz ECRIS are presented.

Ion acceleration mechanism in plasma focus devices

AbstractPlasma focus is one type of ion source with energy up to few MeV. While some efforts have been made to understand the physics of ion beam acceleration in plasma focus devices (PFD), an acceptable clarification does not exist yet. In this work, the procedure of ions) electrons) acceleration in PFDs to the MeV energy is investigated theoretically. Moreover, the trajectory of electrons (ions) and their angular distribution are studied. The simulations are carried out by COMSOL Multiphysics version 5.2 for a 4.5 kJ Mather type PFD. The results of simulations and calculations show that trapped ions in the negative potential of electrons, their movement toward the top of the anode and the drift motion due to electrical and magnetic fields near the top of the anode are the main causes of high energy electrons (ions) production and acceleration.

Characterization of Leucaena (<em>Leucaena leucephala</em>) oil by direct analysis in real time (DART) ion source and gas chromatography

For the first time, we report the characterization of triacylglycerols and fatty acids in Leucaena (Leucaena leucephala) oil [LUCO], an unexplored nontraditional non-medicinal plant belonging to the family Fabaceae. LUCO was converted to fatty acid methyl esters (FAMEs). We analyzed the triacylglycerols (TAGs) of pure LUCO and their FAMEs by time-of-flight mass spectrometry (TOF-MS) followed by multivariate analysis for discrimination among the FAMEs. Our investigations for the analysis of LUCO samples represent noble features of glycerides. A new type of ion source, coupled with high-resolution TOF-MS was applied for the comprehensive analysis of triacylglycerols. The composition of fatty acid based LUCO oil was studied using Gas Chromatography (GC-FID). The major fatty acid components of LUCO oil are linoleic acid (52.08%) oleic acid (21.26%), palmitic acid (7.91%) and stearic acid (6.01%). A metal analysis in LUCO was done by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The structural elucidation and thermal stability of LUCO were studied by FT-IR, 1H NMR, 13C NMR spectroscopic techniques and TGA-DSC, respectively. We also measured the cytotoxicity of LUCO.

Molecular carbon nitride ion beams for enhanced corrosion resistance of stainless steel

A novel approach is presented for molecular carbon nitride beams to coat stainless surfaces steel using conventional safe feeder gases and electrically conductive sputter targets for surface engineering with ion implantation technology. GNS Science’s Penning type ion sources take advantage of the breaking up of ion species in the plasma to assemble novel combinations of ion species. To test this phenomenon for carbon nitride, mixtures of gases and sputter targets were used to probe for CN+ ions for simultaneous implantation into stainless steel. Results from mass analysed ion beams show that CN+ and a variety of other ion species such as CNH+ can be produced successfully. Preliminary measurements show that the corrosion resistance of stainless steel surfaces increased sharply when implanting CN+ at 30keV compared to reference samples, which is interesting from an application point of view in which improved corrosion resistance, surface engineering and short processing time of stainless steel is required. The results are also interesting for novel research in carbon-based mesoporous materials for energy storage applications and as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost.

A new ion-beam laboratory for materials research at the Slovak University of Technology

An ion beam laboratory (IBL) for materials research has been commissioned recently at the Slovak University of Technology within the University Science Park CAMBO located in Trnava. The facility will support research in the field of materials science, physical engineering and nanotechnology. Ion-beam materials modification (IBMM) as well as ion-beam analysis (IBA) are covered and deliverable ion energies are in the range from tens of keV up to tens of MeV. Two systems have been put into operation. First, a high current version of the HVEE 6MV Tandetron electrostatic tandem accelerator with duoplasmatron and cesium sputtering ion sources, equipped with two end-stations: a high-energy ion implantation and IBA end-station which includes RBS, PIXE and ERDA analytical systems. Second, a 500kV implanter equipped with a Bernas type ion source and two experimental wafer processing end-stations. The facility itself, operational experience and first IBMM and IBA experiments are presented together with near-future plans and ongoing development of the IBL.

ION SOURCE FOR A SINGLE PARTICLE ACCELERATOR

This paper proposes a method to obtain very low beam current on the injection side of an particle accelerator. By using a combination of a well known ion source type and a short photo-emissive laser pulse, very low amount of ions can be created. The method could be used in the ion source of various types of the accelerators, where very low beam current is essential. The design is adapted to build a compact internal ion source and the dimensions of the device are adjusted to fit central region of the cyclotron U-120M. The functional parameters of the device are discussed and the ammount of the produced ions is estimated.

Fabrication of Potassium Ion Source and its Emission Characteristics

In this study, we fabricated the K + ion source for the various purposes and investigated the emission characteristics. The fabricated K + ion source was painted in the tungsten filament to make filament type ion source. The RGA spectra show that the filament type K + ion source has a good out gassing character, so it can be used in the ultra-high vacuum system. The maximum K + ion current was 20 mA when filament temperature was 1410 K and filament potential was 50 V. When the filament temperature was 1070 K, the initial beam current was 50 mA and decreased only by 2% during 4 hours. The emitting energy was measured to be 2.04 eV. This low value means that the fabricated specimen is a good K+ ion source. We conclude that this filament type ion source can be used in various fields, including the LEIS research.