A. Efremov

The L3A facility at the Vinča Institute: Surface modification of materials, by heavy ion beams from an electron cyclotron resonance ion source

This article describes the L3A experimental facility for surface modification of materials at the Vinca Institute of Nuclear Sciences, in Belgrade. This facility was completed and put into operation in May 1998. It is connected to the mVINIS ion source, an electron cyclotron resonance ion source capable of producing a wide range of multiply charged ions from gaseous and solid substances. The heavy ion beams obtained from mVINIS are separated by charge to mass ratio (q/m) and transported to the target chamber for sample irradiation and modification. The target chamber is equipped with a multipurpose target holder, an electron-beam evaporation source for thin layer deposition, a residual gas analyzer, and other auxiliary equipment. There is also an additional low energy argon ion source for target preparation/sputtering and for ion beam assisted deposition. In this article we describe the layout and performances of the L3A facility, the experience gained during 1 yr of operation, and the requirements impose...

Status of the ion source DECRIS-SC

A “liquid He-free” superconducting electron cyclotron resonance ion Source DECRIS-SC, to be used as an injector for the compact IC-100 cyclotron, has been designed and built in cooperation between the FLNR and LHE (JINR). The main feature is that a compact refrigerator of the Gifford-McMahon type is used to cool the solenoid coils. Due to a very small cooling power at 4.2K (about 1W) our efforts were aimed at optimizing the magnetic structure and minimizing external heating of the coils. The maximum magnetic-field strengths are 3 and 2T in the injection and extraction regions, respectively. When the source had been assembled and magnetic field measured, the ion source was immediately installed at the injection line of the cyclotron. During the first tests, which were run only a few days, some problems arose due to a relatively poor efficiency of the beam transport and analyzing line. From the moment of the first reliable beam production up to now the ion source has been operating continuously for the cycl...

Production of intense 48Ca ion beam at the U-400 cyclotron

Production of the intense accelerated 48Ca ion beam is the key problem in the experiments on synthesizing of new heavy nuclei. For this purpose an axial injection system with the electron cyclotron resonance (ECR)-4M ion source was created for the U400 cyclotron. The task was to achieve an accelerated beam with an intensity of 0.5 pμA of 48Ca5+ at the 48Ca consumption of ∼0.5 mg/h. To solve this problem, a new method for the solid material feed into the ECR source was developed. The combination of a micro oven with a hot tantalum sheet inside the discharge chamber allowed the production of intense beams of ions of metals with relatively low melting point. The present article describes the method, technique, and experimental results on the production of 48Ca ion beam at the U-400 cyclotron from the ECR-4M ion source. The analysis of the working substance balance in the ion source including the ion beam extraction and material regeneration is performed. The analysis based on the experimental data has shown ...

Design aspects and status of construction of the mVINIS ion source

The mVINIS ion source is a multiply charged heavy ion source based on the electron cyclotron resonance effect. This machine is a part of the Tesla Accelerator Installation, an ion accelerator facility whose construction has been going on at the VINCA Institute of Nuclear Sciences in Belgrade, Yugoslavia. mVINIS is an advanced version of the Dubna electron cyclotron resonance ion source 14-2, constructed at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. It is a complete injector, consisting of an ECR ion source, focusing and steering elements, an analyzing magnet, a vacuum system, and an ion beam diagnostic system. The main parts of mVINIS have been designed and manufactured at JINR, while the vacuum equipment, power supplies, ion beam diagnostics, and control system were purchased elsewhere. The preliminary testing (magnetic field measurements, vacuum testing, testing of the ECR ion source) has been performed at JINR, and the final assembly of the mVINIS and measurement of the ion beam ...

Performance of the ion source DECRIS-14-2

The Dubna electron cyclotron resonance ion source DECRIS-14-2 was put into regular operation at the U-400M cyclotron in the beginning of 1995. During the past two years the source has produced a wide range of ion beams for physics experiments as well as for the testing of the beam transport lines and the cyclotron itself. Ions of gases, such as He, N, O, Ne, and Ar were successfully delivered and accelerated in the cyclotron. The ion source has shown good performance especially in the case of middle charge state ions (e.g., 600 eμA of Ar8+) as well as high operational reliability. Significant progress in metal ion production has been achieved by introducing a new microoven for the evaporation of metal samples. This microoven in combination with an additional tantalum sheet installed inside the discharge chamber has made it possible to obtain Li2+ ion beams in excess of 200 eμA.

Progress report on the mVINIS ion source

The mVINIS ion source is one of the major machines of the TESLA Accelerator Installation, at the Vinca Institute of Nuclear Sciences. It is an electron cyclotron resonance ion source with multiple applications. It can serve as an injector for an isochronous cyclotron providing heavy ions for several high energy experimental channels (radiation physics, radiation biology, physics of thin crystals, nuclear physics) or as a stand alone machine directly delivering multiply charged ions to the low energy experimental channels (physics of multiply charged ions, surface physics, surface modification of materials). This article describes the completion of mVINIS that included the finalization of its safety and control systems, the fine adjusting and calibration of its gas inlet system, and the installation of the solid substance inlet system. The recent results obtained with ion beams produced from gases and solid substances are presented, showing the wide capabilities of this machine. The ion beams obtained from...

PRODUCTION AND ACCELERATION OF TRITIUM ION BEAM AT THE U-400M CYCLOTRON

The tritium ion beam was required for study of 4H and 5H resonance states in neutron transfer reactions t+t→5H+p and t+t→4H+d. Experiments were performed at the separator ACCULINNA [1]. In the report the main aspects of the tritium ion beam production and the result of the cyclotron operation are presented.

Electron cyclotron resonance ion source DECRIS-4 for the U400 cyclotron

The electron cyclotron resonance ion source DECRIS-4 has been designed and constructed at the FLNR to be used as a second injector of heavy multiply charged ions for the U-400 cyclotron. After the modification of the injection side this source can be also used as a “charge breeder” (the “1+→n+” method) for the second phase of the Dubna radioactive ion beams project. The main feature of the ion source design is the creation of the extended resonance zone in a comparatively compact electron cyclotron resonance ion source. For this purpose the axial magnetic field is formed with a flat minimum. In this case the superposition of the axial magnetic field and the radial field of the permanent-magnet hexapole, made from NdFeB, allows one to create a larger resonance volume. For the plasma heating a microwave frequency of 14 GHz is used. In this paper we will present the basic design features of the ion source, including the results of the magnetic-field measurements. Some preliminary results of ion source tests ...

The superconducting magnet system with a cryocooler for the ion source Decris-SC

A superconducting magnet system (SMS) for the multicharged ion source DECRIS-SC was designed and manufactured at the Joint Institute for Nuclear Research. Successful tests of the SMS were conducted in late 2003 and early 2004. The peculiarities of this system are stipulated by the use of a cryocooler 1 W in power for the cryostating of the magnet and also by the special configuration of the magnetic field demanded for the source of ions. Four coils ensure the induction of a magnetic field on the axes of the source of up to 3 T (the stopper ratio of ∼6), which considerably extends the possibilities of the ion source from the point of view of producing intense highly charged ion beams. The problem of compensating the large forces of interaction between the coils and surrounding iron yoke in this magnet has been successfully solved, and a reliable suspension of the magnet in a cryostat realized. To compound the windings, which work in vacuum at indirect cryostating, prepreg (thermosetting fiberglass fabric impregnated with epoxide) is used. A new technology of superconducting magnet protection has been applied with the help of sectionalized windings, using passive elements of protection based on “cold” diodes and resistances. A new technology of active protection has also been applied, with normal zone detectors and heaters.

Results of the ECR ion sources operation at the FLNR (JINR) cyclotrons

In the report the main results on production of ion beams from the ECR4M and DECRIS-14-2 ion sources will be presented. Many of the elements required for acceleration at the FLNR cyclotrons are available in the solid state. For production of these beams the evaporator and MIVOC technique were used. In the report the main emphasis is given to production of ions of enriched isotopes, such as 26Mg, 48Ca, 58Fe.