Production Of Metal Ion Beams Research Articles

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.

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.

Production of metallic ion beams by electron cyclotron resonance ion sources equipped with inductive heating ovens at the Institute of Modern Physics.

A high-temperature oven based on the inductive heating technology was developed successfully at the Institute of Modern Physics in 2019. This oven features a durable operation temperature of over 2000 °C inside the tantalum susceptor. By carefully designing the oven structure, the material compatibility issue at high temperature has been successfully solved, which enables the production and routine operation of refractory metal ions with SECRAL-II (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou No. 2). To further apply this type of oven to the room temperature ECR ion sources LECR4 and LECR5 (Lanzhou Electron Cyclotron Resonance ion source No. 4 and 5), a mini-inductive heating oven has been fabricated and tested in 2020. By directly evaporating calcium oxide, some high charge state calcium beams have been produced successfully, such as 52 euA of 40Ca16+, 30 euA of 40Ca17+, and 12 euA of 40Ca18+. The detailed design and testing results will be presented and discussed.

Production of intense metal ion beams from ECR ion sources using the MIVOC method

The production of metal ion beams by electron cyclotron resonance (ECR) ion sources using the MIVOC (Metal Ions from Volatile Compounds) method is described. The method is based on the use of metal compounds which have high vapor pressure at room temperature, e.g., C2B10H12, Fe(C5H5)2, etc. Intense ion beams of B and Fe were produced using this method at the FLNR JINR cyclotrons. Experiments on the production of cobalt, chromium, vanadium, germanium, and hafnium ion beams were performed at the test bench of ECR ion sources. Main efforts were put into production and acceleration of 50Ti ion beams at the U-400 cyclotron. The experiments on the production of 50Ti ion beams were performed at the test bench using natural and enriched compounds of titanium (CH3)5C5Ti(CH3)3. In these experiments, 80 μA 48Ti5+ and 70 μA 48Ti11+ beam currents were obtained at different settings of the source. Following successful tests, two 3-week runs were performed with 50Ti beams at the U-400 cyclotron aimed to perform experiments on the spectroscopy of superheavy elements. The intensity of the injected 50Ti5+ beam was 50–60 μA. The source worked stably during experiments. The compound consumption rate was determined at about 2.4 mg/h, which corresponded to the 50Ti consumption of 0.6 mg/h.

A discussion on the application and production of metal ion beams

Metal ion beams, which are used in surface modification of metals and alloys as ion beam micrometallurgy, are promising candidates for advanced applications in semiconductors and insulators. Doping with transition metal and rare-earth metal ions in semiconductors and insulators to form metallic nanoclusters attracted much more attention recently, since their applications in diluted magnetic semiconductors, electroluminescent devices, giant magnetic resistance, etc. In this paper, some experiments for metal ion beams will be presented, and various methods and technologies for the production of metal ion beams will be discussed.

Ion beam development for the needs of the JYFL nuclear physics programme

The increased requirements towards the use of higher ion beam intensities motivated us to initiate the project to improve the overall transmission of the K130 cyclotron facility. With the facility the transport efficiency decreases rapidly as a function of total beam intensity extracted from the JYFL ECR ion sources. According to statistics, the total transmission efficiency is of the order of 10% for low beam intensities (I(total)< or =0.7 mA) and only about 2% for high beam intensities (I(total)>1.5 mA). Requirements towards the use of new metal ion beams for the nuclear physics experiments have also increased. The miniature oven used for the production of metal ion beams at the JYFL is not able to reach the temperature needed for the requested metal ion beams. In order to fulfill these requirements intensive development work has been performed. An inductively and a resistively heated oven has successfully been developed and both are capable of reaching temperatures of about 2000 degrees C. In addition, sputtering technique has been tested. GEANT4 simulations have been started in order to better understand the processes involved with the bremsstrahlung, which gives an extra heat load to cryostat in the case of superconducting ECR ion source. Parallel with this work, a new advanced ECR heating simulation program has been developed. In this article we present the latest results of the above-mentioned projects.

Reduction of the carbon contamination of an electron cyclotron resonance ion source

The MIVOC method can be used for the production of metal ion beams with an electron cyclotron resonance ion source. The drawback of the method is the inevitable carbon contamination of the plasma chamber, which lowers the performance of the ion source. After the production of metal ion beams, the carbon contamination has to be removed in order to return the maximum performance of the ion source. In this work the cleaning of the plasma chamber with the aid of nitrogen and oxygen plasmas has been studied. The achieved extraction rate of carbon was found to be two times higher with oxygen plasma. It was also found that the carbon contamination is concentrated on the area of the plasma chamber surface covered by the electron flux escaping from the plasma.

ECR ion sources at the Institute of Modern Physics: From classical to fully superconducting device

Electron cyclotron resonance (ECR) ion sources are used for cyclotron complex and atomic physics research at the Institute of Modern Physics (IMP). Intense beams of highly charged gaseous and metallic ions could be produced by the IMP 14.5 GHz ECR ion source (LECR2-Lanzhou Electron Cyclotron Resonance Ion Source No. 2). A particular emphasis has been put on the production of metallic ion beams recently. Metallic ion beams of Mg, Ca, Fe, Ni, Cu, Zn, and Pb were tested at the IMP 14.5 GHz ECR ion source (LECR2) to improve beam intensities and long-term stability. A new ECR ion source (Lanzhou Electron Cyclotron Resonance Ion Source No. 3), an upgraded version of the IMP 14.5 GHz ECR (LECR2) but with double-frequency wave heating (10 GHz+14.5 GHz), is under commissioning. The preliminary results of this new source will be presented. To satisfy the requirements of the heavy ion cooling storage ring that is under construction at IMP, a fully superconducting ECR ion source (Lanzhou Electron Cyclotron Resonance Ion Source with Superconducting Coils) with a completely new structure is being developed for the production of intense heavy ion beams of very high charge states, such as Xe30+ and U40+. The superconducting magnet consists of three axial solenoid coils and six saddle-curved sextupole coils with a cold iron structure as field booster and clamp. At full excitation, this magnet assembly will produce maximum peak fields on axis of 4.0 T at the injection, 2.2 T at the extraction region, and a radial sextupole field of 2.0 T at plasma chamber wall. The design features and status of this new superconducting ECR ion source will be presented.

Metal ions from the volatile compounds method for the production of metal ion beams

The metal ions from the volatile compounds (MIVOC) method was developed at the Accelerator Laboratory, University of Jyväskylä, in order to produce metal ion beams with the source material at or near room temperature conditions. It has been used with the JYFL-ECR ion source since 1993 and has turned out to be both simple and reliable. The method was adopted at several laboratories. Up to the present time, at least 17 MIVOC beams were produced (C, Mg, Si, Cl, Ti, V, Cr, Fe, Co, Ni, Ge, Mo, Ru, Sn, I, W, and Os). With the MIVOC technique it was found possible to operate the JYFL-ECR ion source with compounds of metals, either powders or liquids, that have a room temperature vapor pressure of the order of 1E–3 mbar or higher. The MIVOC method has turned out to be very economical in use since a typical material consumption rate is about 0.3 mg/h. This corresponds to the consumption rate of gases. Due to the simplicity of the system the duty-off time of the ion source is minimized. In this article, the basis of the MIVOC method, phenomena related to it and some results will be presented.

Recent developments for metallic ion production at the National Superconducting Cyclotron Laboratory

This article describes studies performed on the National Superconducting Cyclotron Laboratory’s Superconducting-ECR (electron cyclotron resonance) ion source for the production of metallic ion beams. The Room Temperature-ECR ion source as the workhorse for generating metallic ion beams using a solid feed system will be superceded in the future by the Superconducting-ECR ion source. A series of tests were carried out with a Langmuir probe introduced axially into the plasma chamber of the Superconducting-ECR ion source. These tests determined the location and shape of the plasma and its floating potential. The results presented show the effect of source bias and axial magnetic field on the plasma boundary. Some preliminary results for gold sputtering are also included. The use of a solid metal, saturated in deuterium, to produce deuterium beams in the Room Temperature-ECR ion source has also been studied.

High current implantation equipment

High current ion implantation technology has been getting a great deal of attention in the fields of surface modification and new material formation. For such diverse applications a high current implanter with a sputter-ion source has been developed and stable production of metal ion beams has been demonstrated. High melting point metal ions such as Cr +, Fe + and Pd + were successfully extracted at a beam current of 420, 340, and 260 μA, respectively. A monitor system of metal vapor production for a stable beam has been tested using an optical spectrometer and its usefulness was confirmed.