High Current Beams Of Metal Ions Research Articles

Extraction of high current Cr ion beam from a multicusp metal ion source

Improvements have been made in a metal ion source, which made it possible to produce high density metal vapor plasma for extracting high current metal ion beams. Experiments of chromium ion beam extraction were performed. The ion beam current reached 250 mA at the extraction voltage of 36 kV. Furthermore, stable operation was achieved at the extracted current of 117 mA. The temporal drift of ion beam current was within ±1% for 1 h.

Improvement in wear characteristics of steel tools by metal ion implantation

The annual economic loss induced by wear damage of steel tools is estimated to be DM 34 billion. Ion implantation is known to be a promising method for improving the wear behaviour of metal surfaces. The effect of nitrogen implantation into steel has been investigated by a number of workers and good results have been obtained for several types of steel, especially for steel with high chromium content. However, few investigations of the effect of metal ion implantation into steel have been made. We have investigated the effect of metal ion implantation into high speed steel dies, using high current metal ion beams from a repetitively pulsed vacuum arc ion source. The testing method was, the upsetting, which is comparable to actual forming processes and stimulates the wear strain of the tools used in the metal forming industry. Here we describe the metal ion implantation facility and the wear testing apparatus and procedure, and discuss the results we have obtained.

Large Scale Ion Beam Equipment and Processing - Review of Ammtra Project -

An R&D project of large scale ion beam equipment and processing is being carried out from 1986 till 1994. The project includes R&D of five ion beam systems and three material processes for surface modification. The five equipment R&D projects are:(1)High current metal ion beam system,(2)Integrated high current ion beam system,(3)Ionized multiple beam system with high deposition rate,(4)High energy ion beam system,(5)Gas-phase focused ion beam system.The three materials processing R&D projects are:(1)Glass surface modification,(2)Metal surface modification,(3)Low scattering multilayer film deposition. This paper reviews recent progress on development of the project. This work was conducted in the program: ’Advanced Material Processing and Machining System’ consigned to AMMTRA from the New Energy and Industrial Technology Development Organization, which is carried out under the Industrial Science and Technology Frontier Program enforced by the Agency of Industrial Science and Technology of Japan.

Ion species measurement of high current metal ion beams extracted from a multicusp ion source

Ion charge state and impurities extracted from a multicusp ion source have been studied with the use of a magnetic momentum mass analyzer. Impurities contained in high current metal ion beams are crucible materials (such as Al2O3, BN, Y2O3, C) and high melting point materials (such as Mo, Ta, W). To reduce these impurities, the dependence of the impurity on the arc discharge voltage has been investigated experimentally. Amounts of impurities and multicharged ions are decreased with arc discharge voltage. For example, at the arc discharge voltage of 60 V, aluminum ion beam contains 1% impurities and 4% multicharged ions, and at the arc discharge voltage of 20 V, impurities and multicharged ions are less than 1% in all. High-purity single-charged metal ion beams have been obtained.

High-current metal-ion source for ion implantation

High-current metal-ion beams, as needed for material modification of metal surfaces, can be produced using the MEVVA ion source. In this article a brief description of the ion source is given, and its operational characteristics and preliminary results are presented. A range of metal ions such as Cu, Ti, Al, Fe, Mo, and W, etc., have been extracted from the source. The ion-beam current is 0.5–1 A (total current in all charge states) and is a function of the cathode material, arc current, and extractor voltage. The beam pulse width is 300–550 μs, the repetition rate several pulses per second, the extraction voltage about 30 kV, and the arc current 150–350 A. The extraction system has a set of three multiaperture extractor grids, including three different sizes: 37 holes 2 mm in diameter, and 207 and 495 holes 1 mm in diameter. The operating pressure is in the 2×10−6-Torr range, obtained with a diffusion pump.

High-current metal-ion beams with energies up to 45 keV u−1

The high-current ion source CHORDIS † † Manufactured under GSI licence by Danyfysik A/S, Jyllinge, Denmark. is intended to generate d.c. and pulsed beams of at least milliampere intensities of any element. Beside gas and oven versions of this ion source a sputter version has been developed and investigated with aluminium, titanium, iron, copper, molybdenum and tantalum electrodes. Stable beams of these metals can be extracted from the source for several hours. The CHORDIS source is used at GSI at a 50 kV test bench and at the 300 kV test accelerator. At the second beam line of the test accelerator h radio frequency quadrupole postaccelerator has been installed which accelerates milliampere ion beams up to 45 keV u −1. Parameters of the different beam lines available at GSI for implantation experiments are summarized. With this equipment high-dose implantation of heavy ions to depths of about 1 μm is possible. Experiments by external research groups started in 1987.

High current metal ion beam transport in the UNILAC injector at GSI

Transport of high current beams of metal ions through the injector beam line of the heavy ion linear accelerator, UNILAC, has been demonstrated using the MEVVA high current metal ion source. Improved operation of the MEVVA source has been achieved in various ways, including shot-to-shot reproducibility of the beam pulse, beam noise, pulse shape, and absence of “missing” pulses. The source was first tested on a high current test stand beam line, and then moved over to regularly used UNILAC injector terminal. Flat and reproducible titanium ion beam pulses were efficiently transported through the system from the ion source to the Wideroe preaccelerator entrance. A beam current of 20 mA (pulse current) of titanium (all charge states, q = 1, 2, 3) was accelerated to an energy of 280 Q keV through the single-gap accelerating structure, and a current of over 5 mA of Ti 2+ was measured at the Wideroe entrance 13 m downstream.

Development of high current metal ion beam source

A magnetic multipole ion source with some modifications to sustain high density metal vapour plasma has been developed and investigated. The following results are experimentally obtained for aluminium plasma: (1) the inside of the ion source is heated up to about 1500 K to sustain the metal vapour density necessary for a discharge; (2) the high purity aluminium plasma is produced; (3) the ion current density is over about 10 mA/cm 2; and (4) the radial uniformity of ion current density is about ± 5% over a radius of 3 cm.

Intense metal ion beam formation by an impregnated-electrode-type liquid metal ion source

High current metal ion beams of several hundred μA for various single metal elements were obtained by single-point emission from an impregnated-electrode-type liquid metal ion source. For high efficiency ion beam transport, a double-lens system was designed, which consists of a physically asymmetric lens and an einzel lens, the former for suppressing large beam divergence just after the ion extractor and the latter for forming a suitable transport beam. Using this lens system, about 210 μA of lithium ion current was transported over a distance of 0.4 m within an optical column 2 cm in diameter. After mass separation, about 70 μA of Li + was obtained. To further intensify the metal ion current, a tip with three emission points in one dimension was developed. By three-point emission, 1.3 mA of germanium ion current was extracted. Based on these results, the impregnated-electrode-type liquid metal ion source is considered suitable as a multipurpose metal ion source.

Production of high-current metal ion beams

The increasing usage of ion implantation to modify the chemical and surface sensitive mechanical properties of materials typically requires fluences of 10 17 ions/cm 2. In order to implant test hardware (e.g., ball bearings) to such high influences in a reasonable period of time it is necessary to employ ion beam currents with intensities of a hundred-microampere or more. This paper will describe the modifications made in the ion source of the NRL Extrion/Varian 200-20A2F ion implanter to produce high current metal ion beams utilizing an internal chlorination technique. Several charge material source geometries and carrier gas combinations have been tried and compared. Beam currents of 100 μA or more intensity have been routinely obtained for most metal species attempted, with 500–1000 μA intensities obtained for some commonly run species (e.g., 52Cr + and 48Ti +). This paper will present (1) a compilation of ion species and intensities obtained, (2) typical ion source operating parameters and lifetimes, and (3) evidence of ion source “poisoning effects”.