High-temperature Ion Source Research Articles

Quo vadis Spectroscopy?

Since the early days of modern chemistry, analytical chemistry always tried to offer solutions to real-life problems. This is how, in the midst of the Industrial Revolution, Margueritte developed the titrimetric determination of iron using the chameleon solution (potassium permanganate). In 1860, for the first time, Bunsen and Kirchhoff used element-specific light emission and absorption of flame-evaporated alkali metal salts for qualitative analysis. Their discovery was groundbreaking because the analytical sensitivity and detection capability of the proposed method was several orders of magnitude lower than that of the contemporary classical analytical ones. Application of this method, leading to the establishment of spectroscopic techniques, also allowed the discovery of about ten chemical elements. Another timeless merit of spectroscopy is the ability to determine the elemental composition of a star in a distant galaxy. In the second half of the 20th century, an era of rapid development of instrumental analysis, atomic spectroscopy also brought several revolutionary results. One such breakthrough was the reduction of the sample volume required for analysis down to microliters with the introduction of graphite furnace atomic absorption spectrometry (GFAAS). The detection limit of GFAAS also decreased by several orders of magnitude. Another important advance was the combination of inductively coupled plasma as a high-temperature ion source with a mass spectrometer (ICP-MS). In the late 1980s, the hyphenation of atomic spectrometric devices to chromatographs, aiming at elemental speciation, also emerged. In Central and Eastern Europe, spectroscopic research was driven by the embargo of the Coordinating Committee for Multilateral Export Controls established by the Western Bloc during the Cold War. In this emerging era, scientific research and applications went hand in hand. Therefore, the science education program and fundamental research were very strong in those countries, contributing considerably to the development of spectrochemistry in Hungary. By the end of the 20th century, development of new equipment and procedures was increasingly carried out by instrument manufacturers, and fundamental research at universities and institutes was relegated to second place. Analytical chemistry has experienced a considerable shift from determination of inorganic compounds and small organic molecules towards that of large (bio)molecules. Expansion of the application of analytical chemistry to forensic, environmental and biochemical questions has been observed and the role of atomic spectrometric techniques seemed to fade away. However, sheer use of these high-performance instruments is not always appropriate or cost-effective; the reliability of the results and elimination of interference must be thoroughly explored. However, when publishing such results, there is a risk that our communications will be rejected due to lack of novelty. Nevertheless, carrying out fundamental research cannot be avoided, as it is not possible to offer appropriate decisions to stakeholders based on questionable results. Presently, GFAAS and ICP-MS allow reliable quantitative determination of virtually any element in any sample. Recently, microwave plasma using nitrogen isolated from the air was launched on the market. This device requires significantly lower operating costs compared to the conventional ICP and reliable simultaneous multi-element analysis has also become possible. Another promising direction is single-particle ICP-MS applied for the characterization of inorganic nanoparticles. Most of the articles of the current issue of BrJAC also demonstrate that atomic spectrometry has become indispensable in many areas of our life. Enjoy reading the current issue!

The Effect of Plasma Density on the Degree of Suppression of Analyte Signals in ICP-MS

Possible effects of ionization phenomena on the analytical signal in inductively coupled plasma mass spectrometry with a high-temperature ion source are considered. The dependences of the degree of suppression of ion signals on the electron density are calculated and experimentally determined for ions of matrix and impurity elements. It is shown that the degree of signal suppression depends rather strongly on the electron density in the analytical zone in the presence of matrix elements with different first ionization potentials. The effects of the inductive plasma power and sputtering argon rate on the sensitivity of the mass spectrometer are studied by the example of an ICP-MS mass spectrometer (Agilent Technologies). The experimental results showed that the origin of the suppression of the analyte signals at the output is apparently associated with the ion–electron recombination of ions (both matrix and impurity ones) in the plasma region.

Влияние плотности плазмы на степень подавления сигналов аналитов в ICP-MS

Рассмотрены возможные влияния ионизационных явлений на аналитический сигнал в методе масс-спектрометрии с индуктивно связанной плазмой с высокотемпературным источником ионов. Рассчитаны и экспериментально определены зависимости степени подавления ионных сигналов от концентрации электронов для ионов матричных и приместных элементов. Показано, что степень подавления сигналов достаточно сильно зависит от концентрации электронов в аналитической зоне в присутствии матричных элементов с различными по величине первыми потенциалами ионизации. На примере масс-спектрометра ICP-MS (Agilent Technologies) изучены влияния мощности индуктивной плазмы и скорости распылительного аргона на чувствительность масс-спектрометра. Результаты эксперимента показали, что причины подавления сигналов аналитов на выходе, по-видимому, связаны с ионно-электронной рекомбинацией ионов (как матричных, так и примесных) в области плазмы. Ключевые слова: масс-спектрометрия с индуктивно связанной плазмой, матричный эффект, рекомбинация ионов, концентрация электронов, подавление ионных сигналов.

Thermal-electric coupled-field finite element modeling and experimental testing of high-temperature ion sources for the production of radioactive ion beams

In isotope separation on line facilities the target system and the related ion source are two of the most critical components. In the context of the selective production of exotic species (SPES) project, a 40 MeV 200 μA proton beam directly impinges a uranium carbide target, generating approximately 10(13) fissions per second. The radioactive isotopes produced in this way are then directed to the ion source, where they can be ionized and finally accelerated to the subsequent areas of the facility. In this work both the surface ion source and the plasma ion source adopted for the SPES facility are presented and studied by means of numerical thermal-electric models. Then, numerical results are compared with temperature and electric potential difference measurements, and finally the main advantages of the proposed simulation approach are discussed.

Development of radioactive ion beam production systems for Tokai Radioactive Ion Acceleration Complex—High temperature ion source for short-lived isotopes

We have developed a new ion source system in the isotope separator on-line at Japan Atomic Energy Agency, for separation of short-lived isotopes produced by proton-induced fission of (238)U. The ion source system is a forced electron beam induced arc discharge version E type ion source with a target container. We successfully operated this system at 2000 degrees C as a result of reductions in volume of the ion source and the target container, introduction of heating method by electron bombardment, and improvement to the heat shield. This new ion source system was tested using (238)U of 640 mg/cm(2) with a proton primary beam of 30 MeV, 350 nA. Release times were measured for Kr, In, and Xe. The values of release times are 2.6 s for Kr, 1.8 s for In, and 4.6 s for Xe. In this work, the ion source system enabled us to mass-separate short-lived isotopes such as (93)Kr(T(1/2)=1.286 s), (129)In(T(1/2)=0.61 s), and (141)Xe(T(1/2)=1.73 s) with intensity of 10(3) ions/s.

Extension of the Bissell–Johnson plasma-sheath model for application to fusion-relevant and general plasmas

This article presents an approach to solving a special Fredholm-type integral equation of the first kind with a particular kernel containing a modified Bessel function for applications in plasma physics. From the physical point of view, the problem was defined by Bissell and Johnson (B&J) [Phys. Fluids 30, 779 (1987)] as a task to find the potential profile and the ion velocity distribution function in a plane-parallel discharge with a Maxwellian ion source. The B&J model is a generalization of the well-known Tonks–Langmuir (T&L) [Phys. Rev. 34, 876 (1929)] discharge model characterized by a “cold” ion source. Unlike the T&L model, which can be readily solved analytically, attempts to solve the B&J model with a “warm” ion source have been done only numerically. However, the validity of numerical solutions up to date remains constrained to a rather limited range of a crucial independent parameter of the B&J integral equation, which mathematically is the width of a Gaussian distribution and physically represents the ion temperature. It was solved only for moderately warm ion sources. This paper presents the exact numerical solution of the B&J model, which is valid without any restriction regarding the above-mentioned parameter. It is shown that the ion temperature is very different from the temperature of the ion source. The new results with high-temperature ion sources are not only of particular importance for understanding and describing the plasma-sheath boundary in fusion plasmas, but are of considerable interest for discharge problems in general. The eigenvalue of the problem, found analytically by Harrison and Thompson [Proc. Phys. Soc. 74, 145 (1959)] for the particular case of a cold ion source, is here extended to arbitrary ion-source temperatures.

High-efficiency target ion sources for radioactive ion beam generation

In this report, high-temperature ion sources are described, which have demonstrated the high ionization efficiency, species versatility, and operational reliability required at isotope-separator-online (ISOL) based radioactive ion beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF). Specific attention is given to the ion optics, operational parameters, thermal transport properties, emittances, and ionization efficiencies of the HRIBF ion sources that have been carefully designed for safe handling in the high-level radiation fields incumbent at such facilities. Included in the article are descriptions and performance data for high-temperature, positive- (electron impact and surface ionization) and negative- (kinetic ejection and surface ionization) ion sources as well as low-temperature, batch-mode negative-ion sources, developed for processing long-lived isotopes that have been the principal contributors to recent successes held at the Holifield Radioactive Ion Beam Facility.

Very high-temperature ion source

This paper represents the next step in the development and research of high-temperature ion sources of refractory metals. The very high-temperature ion source is created on the basis of the already produced high-temperature source for palladium ions. The basic difficulties of such device designing, the successes, and perspective tasks are presented.

High temperature ion sources with ion confinement

Different types of high temperature ion sources such as surface, laser, and electron beam ionization ion sources have been developed and tested in off-line and on-line experiments. All types of developed ion sources have an essential common feature: an existence of the ion confinement inside the ion source cavity.

Beta decay energies and nuclear masses of148Ba,148La and151Pr

Theβ-decay energy of the neutron-rich isotopes148Ba,148La and151Pr has been measured at the Institute Laue-Langevin (ILL). The148Ba- and148La-nuclei were produced using a high-temperature ion source at the OSTIS separator of this institute, whereas samples of151Pr were obtained from the thermal fission of239Pu, used as a target in the mass separator LOHENGRIN. At both instruments,βγ-coincidences were measured with a plastic scintillator telescope and a Ge(I)-detector, together withβ-singles andγ-singles spectra. Theβ-spectra emitted in coincidence with 44γ-lines in the decay of these nuclei have been evaluated. From their endpoint energies, the followingQβ-values have been obtained:Qβ(148Ba)=5115±60keV;Qβ(148La)=7255±55 keV;Qβ(151Pr)=4170±75 keV. Using these results, the nuclear massesA of these nuclei can be calculated with a relative error ΔA/A≃5·10−7. In addition, the two-neutron separation energies and the mass excesses have been derived; the results are compared with recent predictions of theoretical mass calculations.

Level schemes of100Y and100Zr from the beta-decay of mass separated100Sr

The beta-decay of100Sr and the low-spin isomer in the daughter nucleus100Y were investigated from sources of100Sr produced from thermal neutron fission in a high-temperature ion source of the online-separator facility OSTIS installed at the Institut Laue-Langevin (ILL), Grenoble. Gamma-single, gamma-multispectra and gamma-gamma-coincidence measurements were performed resulting in the first level scheme of100Y as well as a considerably extended scheme of100Zr. The schemes are placed in level systematics and implications for the appearance of shape coexistence atN=60 are discussed.

The state of the art of target preparation at the Chalk River Nuclear Laboratories

During the past year, the Chalk River target laboratory has developed several new methods for materials preparation related to nuclear research. These include the preparation of large-area tritium sources for paper document imaging and titanium and tungsten foil windows for water targets and high-temperature ion sources, respectively. The fabrication of ultra-thin titanium tritide sources suitable for a neutrino-mass experiment is being investigated. The preparation of radioactive sources by vacuum sublimation has also been carried out to test the focusing properties and to obtain the response function of the Chalk River iron-free β spectrometer, which will be used in the neutrino-mass experiment.

Operation of a high temperature ion source at the helium-jet on-line isotope separator facility HELIOS

The performance of a high temperature ion source coupled to a helium gas-jet transport system for an efficient mass separation of neutron-rich alkaline earth and lanthanide isotopes is reported and the results of overall efficiency measurements using different cluster materials in the gas-jet are given. A fast, microprocessor controlled tape transport system for γ-spectroscopic studies on short-lived isotopes is described. Some results on the decay of 3.8-s 152Pr are presented.

A high-temperature ion source for the on-line separator OSTIS

Recently a new high-temperature ion source which is heated by electron bombardment to a temperature of 2500°C has been designed and built for use at the on-line separator OSTIS. In the new source independent ionization of the alkaline earth elements Sr and Ba as well as of several rare earth elements was achieved. It is shown that this surface-volume-ionization source type can extend the range of elements accessible for nuclear spectroscopy with the separator OSTIS and first results are reported.

A new high temperature isol ion source

A new high temperature ion source for on-line isotope separation applications has been developed. Off-line efficiencies of up to 13% for Xe have been measured. On-line efficiencies of 3% for Tl while operating in the plasma mode and about 30% for Fr while operating in the thermal-ionization mode have been obtained. The release of Tl from this source has been determined to occur with a half-life of about 0.6 s and Fr release was measured to be as short as 0.8 s.

The Colutron Mark II, a velocity filter isotope separator

The Colutron Mark II is a portable, low intensity isotope separator. The separator which uses a velocity filter as analyzing system has adjustable dispersion, small size and a simple vacuum system as main features. Operating experience and a brief technical description of the velocity filter will be given. A new beam scanning system and a high temperature ion source will also be described.