Versatile Ion Source Research Articles

The new Versatile Ion Source (VIS) for high power proton accelerators

The characteristics of the ideal injector for high power proton accelerators have been studied in the last two years with the TRIPS ion source built at INFN-LNS, Catania and now installed at INFN-LNL, Legnaro. The beam production must obey to the request of high brightness, stability and reliability. The new Versatile Ion Source (VIS) is a permanent magnet version of the TRIPS source with a simpler extraction system and mechanics. Its design permits to operate at 80 kV without a bulky high voltage platform, in order to produce multi-mA beams of protons and H2+. The description of the source design and the expected performances will be presented.

Pre- and postextraction analyses of different charge state ion components produced in a laser ion source

Knowledge of the relative abundance and the energy distributions of various ion species produced in laser ablation plasma is essential both in the fundamental physics ground, to understand the thermalization and expansion dynamics of the plasma plume, and in the applied physics ground, to obtain an efficient and versatile ion source. We present measurements and analyses related to such aspects, both for plasma in free expansion and for the extracted ion bunch. In particular, we characterized the former by means of ion current measurements, employing appropriate Faraday cups and electrostatic spectrometers. With regard to the latter, we performed time-of-flight spectrometry and depth profiling of implanted substrates. The extracted bunch signal showed modulation on time of flight due to the presence of multiply charged ions; depth profiling by x-ray photoelectron spectroscopy also showed a maximum penetration range and a profile modulation compatible with a multienergetic beam. In these experiments we used ultraviolet excimer lasers, at irradiance values in the range of 0.1–10GW∕cm2, to generate plasma from Cu and Al targets. The ion beams were extracted at voltages of tens of kV, dc.

Next generation ECR ion sources: First results of the superconducting 28 GHz ECRIS – VENUS

VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (rare isotope accelerator) front end. The goal of the VENUS ECR ion source project as the RIA R&D injector is the production of 200eμA of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5eμA of U48+, a low current, very high charge state beam. To achieve those ambitious goals, the VENUS ECR ion source has been designed for optimum operation at 28GHz. The nominal design fields of the axial magnets are 4T at injection and 3T at extraction; the nominal radial design field strength at the plasma chamber wall is 2T, making VENUS currently the world’s most powerful ECR plasma confinement structure. Recently, the six year project has made significant progress. In June 2002, the first plasma was ignited at 18GHz. During 2003, the VENUS ECR ion source was commissioned at 18GHz, while preparations for 28GHz operation were being conducted. In May 2004 28GHz microwave power has been coupled into the VENUS ECR ion source for the first time. Preliminary performance-tests with oxygen, xenon and bismuth at 18GHz and 28GHz have shown promising results. Intensities close to or exceeding the RIA requirements have been produced for those few test beams. The paper will briefly describe the design of the VENUS source and its beam analyzing system. Results at 18GHz and 28GHz including first emittance measurements will be described.

Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions

A new ion source has been developed for rapid, noncontact analysis of materials at ambient pressure and at ground potential. The new source, termed DART (for "Direct Analysis in Real Time"), is based on the reactions of electronic or vibronic excited-state species with reagent molecules and polar or nonpolar analytes. DART has been installed on a high-resolution time-of-flight mass spectrometer (TOFMS) that provides improved selectivity and accurate elemental composition assignment through exact mass measurements. Although DART has been applied to the analysis of gases, liquids, and solids, a unique application is the direct detection of chemicals on surfaces without requiring sample preparation, such as wiping or solvent extraction. DART has demonstrated success in sampling hundreds of chemicals, including chemical agents and their signatures, pharmaceutics, metabolites, peptides and oligosaccharides, synthetic organics, organometallics, drugs of abuse, explosives, and toxic industrial chemicals. These species were detected on various surfaces, such as concrete, asphalt, human skin, currency, airline boarding passes, business cards, fruits, vegetables, spices, beverages, body fluids, horticultural leaves, cocktail glasses, and clothing. DART employs no radioactive components and is more versatile than devices using radioisotope-based ionization. Because its response is instantaneous, DART provides real-time information, a critical requirement for screening or high throughput.

Analysis of characteristic parameters of a plasma ion source and of ion-assisted deposited optical thin films

It is well known that ion-assisted deposition (IAD) using a plasma source improves the optical and physical characteristics of optical thin films. A broad-beam cold-cathode plasma source was used in this study. The versatile ion source selected can easily be retrofitted into existing deposition chambers or new installations. This paper discusses characterization of the ions produced by the plasma source and analyzes the properties of thin films produced using the plasma source for IAD. Ion energy measurements were made using an ion energy analyzer for the determination of ion energy distribution functions (IEDFs). IEDFs were measured for three gases; argon, oxygen, and nitrogen. The ion characteristics in oxygen are focused on. The effect of pressure and drive current on the IEDFs of oxygen ions is discussed. Mean ion energies of oxygen as a function of pressure, drive voltage, and drive current were calculated. Since the density and quality of films are related to the ion current density during deposition, the effects of drive voltage, pressure, and the pumping speed of the system are discussed. Characteristics of TiO2 and Ta2O5 films deposited on silicon wafers and microscope slides were investigated. The conditions for moisture stability of these films were analyzed.

Time-gated pulsed glow discharge: real-time chemical speciation at the elemental, structural, and molecular level for gas chromatography time-of-flight mass spectrometry.

A millisecond pulsed glow discharge is used as a versatile ion source for time-gated generation of elemental, structural, and molecular ions. The utility of this ion source for comprehensive chemical analysis of a series of aromatic and halogenated hydrocarbons is illustrated in this manuscript. To highlight the analytical utility of this transient ion source, it was connected to a gas chromatograph for the mass spectrometric determination of mixtures containing benzene, toluene, o-xylene, cymene, tert-butylbenzene, carbon tetrachloride, chloroform, chlorobenzene, tetrachlorethane, and dichlorobenzene. Explicit chemical analysis was accomplished by introducing the GC eluent into a pulsed glow discharge operating at a rate of 100 Hz with a 50% duty cycle. Using three independent digitizers for time-gated acquisition in three separate time regimes, nearly concurrent collection of elemental, structural, and molecular information was accomplished. In general, elemental information was obtained during the first 0.015 ms after the plasma onset; structural information, as ascertained from molecular fragmentation, was obtained during the plateau time regime when the plasma pulse is at a steady state, whereas molecular M(+) and MH(+) ions were obtained during the afterpeak time regime, that is, after the cessation of the plasma power pulse.

Cu–Ti surface-layer mixing by ion-beam modification techniques

The modification of a titanium substrate by copper ions has been performed in a versatile ion source by alternating ion deposition with ion implantation. As indicated by the experimental results, the mixing efficiency for the Cu–Ti system is greatly sensitive to the ion-treatment mode. The mixing efficiency was examined by Auger electron spectroscopy depth profiling. In the α-IBAD mode (the implantation pulse precedes the deposition pulse) the mixing efficiency is noticeably smaller than under β-IBAD treatment (the implantation pulse follows the deposition pulse). To explain the observed difference in Cu–Ti mixing, the “hot” single layer model based on the thermodynamic approach is proposed. Transmission electron microscopy investigations of the Cu–Ti mixed layer revealed numerous Cu 2Ti and Cu 4Ti particles 50–100 nm in size. Different quantities of defects around these particles after the α-IBAD and β-IBAD treatments support the “hot” single layer model. The results obtained show the versatile ion source to be a promising tool for the production of deeply mixed metal layers and studies of the ion-mixing mechanism.

Ion-implantation system for near surface studies

An ion-implantation system designed and fabricated indigenously is described. It consists of a versatile ion source, Einzel lens system, EXH velocity filter, dose measuring equipment, and target chamber. The ion-implantation system fabricated has been used to prepare ion-implanted luminescent phosphors by implanting Sb+ ions into CaS.

The Frankfurt PIG ion source

A small sized, versatile PIG ion source with end extraction is described by which positive ion beams of most of the elements can be produced with intensities in the microampere range. The source operates either with gas or with a mixture of gas and metal vapor. In the latter case the supply of the metal atoms to the gas discharge is done by evaporation or sputtering depending on the kind of metal. A characteristic feature of the source is the small power consumption so that cooling of the source housing by air only is sufficient.

Investigation of an arc discharge ion source with energy selection (CMA)

A versatile ion source system for impact experiments is described. The ions were extracted from an arc discharge and were focused to a cylindrical mirror analyser for energy selection. The discharge was driven with Ar, Ne, N 2 and H 2. Varying parameters it was found that the intensity distribution of the ion beam is mainly influenced by the position of the extraction probe, the plasma density and the pressure in the discharge. The energy distribution is affected by the plasma density and the pressure in the discharge. Minor effects result from the arc voltage.