Takuro Otsuka

Producing multicharged fullerene ion beam extracted from the second stage of tandem-type ECRIS

We have been constructing the tandem-type electron cyclotron resonance ion source (ECRIS). Two ion sources of the tandem-type ECRIS are possible to generate plasma individually, and they also confined individual ion species by each different plasma parameter. Hence, it is considered to be suitable for new materials production. As the first step, we try to produce and extract multicharged C60 ions by supplying pure C60 vapor in the second stage plasma because our main target is producing the endohedral fullerenes. We developed a new evaporator to supply fullerene vapor, and we succeeded in observation about multicharged C60 ion beam in tandem-type ECRIS for the first time.

Accessibility condition of wave propagation and multicharged ion production in electron cyclotron resonance ion source plasma

A new tandem type source of electron cyclotron resonance (ECR) plasmas has been constructing for producing synthesized ion beams in Osaka University. Magnetic mirror field configuration with octupole magnets can be controlled to various shape of ECR zones, namely, in the 2nd stage plasma to be available by a pair mirror and a supplemental coil. Noteworthy correlations between these magnetic configurations and production of multicharged ions are investigated in detail, as well as their optimum conditions. We have been considering accessibility condition of electromagnetic and electrostatic waves propagating in ECR ion source plasma, and then investigated their correspondence relationships with production of multicharged ions. It has been clarified that there exits efficient configuration of ECR zones for producing multicharged ion beams experimentally, and then has been suggested from detail accessibility conditions on the ECR plasma that new resonance, i.e., upper hybrid resonance, must have occurred.

Production of multicharged metal ion beams on the first stage of tandem-type ECRIS

Multicharged metal ion beams are required to be applied in a wide range of fields. We aim at synthesizing iron-endohedral fullerene by transporting iron ion beams from the first stage into the fullerene plasma in the second stage of the tandem-type electron cyclotron resonance ion source (ECRIS). We developed new evaporators by using a direct ohmic heating method and a radiation heating method from solid state pure metal materials. We investigate their properties in the test chamber and produce iron ions on the first stage of the tandem-type ECRIS. As a result, we were successful in extracting Fe(+) ion beams from the first stage and introducing Fe(+) ion beams to the second stage. We will try synthesizing iron-endohedral fullerene on the tandem-type ECRIS by using these evaporators.

Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma

Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection are investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF.

First operation and effect of a new tandem-type ion source based on electron cyclotron resonance

A new tandem type source has been constructed on the basis of electron cyclotron resonance plasma for producing synthesized ion beams in Osaka University. Magnetic field in the first stage consists of all permanent magnets, i.e., cylindrically comb shaped one, and that of the second stage consists of a pair of mirror coil, a supplemental coil and the octupole magnets. Both stage plasmas can be individually operated, and produced ions in which is energy controlled by large bore extractor also can be transported from the first to the second stage. We investigate the basic operation and effects of the tandem type electron cyclotron resonance ion source (ECRIS). Analysis of ion beams and investigation of plasma parameters are conducted on produced plasmas in dual plasmas operation as well as each single operation. We describe construction and initial experimental results of the new tandem type ion source based on ECRIS with wide operation window for aiming at producing synthesized ion beams as this new source can be a universal source in future.

Preliminary results of 4.0-6.0 GHz extraordinary mode experiments on 2.45 GHz ECRIS

Penetration conditions of electromagnetic and electrostatic waves propagating in electron cyclotron resonance (ECR) ion source (ECRIS) plasma in Osaka Univ. have been examined in detail, and its relationship with the production of multicharged ions have been investigated experimentally. It has been clarified that there exists efficient configurations of ECR zones for producing multicharged ion beams, and it has been suggested that new resonances, i.e. upper hybrid resonances, must have occurred. We have been conducting new advanced experiments inducing actively these additional effects to enhance multicharged ion beams by launching extra-ordinary (x) mode waves. We have been trying to apply 4-6GHz x-mode microwaves to the 2.45GHz ECRIS, and in this paper we will describe the preliminary experimental results.Penetration conditions of electromagnetic and electrostatic waves propagating in electron cyclotron resonance (ECR) ion source (ECRIS) plasma in Osaka Univ. have been examined in detail, and its relationship with the production of multicharged ions have been investigated experimentally. It has been clarified that there exists efficient configurations of ECR zones for producing multicharged ion beams, and it has been suggested that new resonances, i.e. upper hybrid resonances, must have occurred. We have been conducting new advanced experiments inducing actively these additional effects to enhance multicharged ion beams by launching extra-ordinary (x) mode waves. We have been trying to apply 4-6GHz x-mode microwaves to the 2.45GHz ECRIS, and in this paper we will describe the preliminary experimental results.

Optimization of Mid-Electrode Potential and Extraction Gap for Miscellaneous Ion Beam from Electron Cyclotron Resonance Ion Source

Our goal is producing and extracting　multicharged ion beams ranged wide mass/charge numbers in the single device. We are constructing the extractor which can be optimized for various ion species. The extractor in an electron cyclotron resonance ion source (ECRIS) consists of three electrodes. We improve the width of gap length between plasma electrode and mid-electrode of the extractor. The width of gap length can be enlarged in 10-65mm. We investigate the behaviors of ion beam currents and the beam losses under different gap and operating pressures. We succeed in extracting ion beams of different plasma parameters efficiently and in suppressing the beam losses by changing the gap length and by applying mid-electrode potential. In addition, we can understand the characteristics of the extractor by using a simple theoretical calculation on the compact modelling for ion beam formation.

Developing Pure Iron Evaporator and Production of Iron Ion Beam in Tandem-Type Electron Cyclotron Resonance Ion Source

Multicharged metal ion beams are applied in various fields. We are planning synthesis of iron-endohedral fullerene by collision reaction in vapor phase in an electron cyclotron resonance (ECR) plasma. We have already succeeded in producing multicharged fullerene ions by using fullerene evaporator in ECR ion source (ECRIS). In a vapor phase synthesis, pure iron vapor is required. However, it is difficult to produce and introduce pure iron vapor into the ECRIS, therefore it is key technology for synthesizing iron-endohedral fullerene. We developed pure iron evaporators by ohmic heating method, and produced iron ion beam in the first stage of the tandem-type ECRIS. The aim of this paper is to investigate properties of new evaporators and to compare with previous researches. As a result, we have succeeded in producing large vapor flux and iron ion beam than the previous researches. We are planning synthesizing iron-endohedral fullerene on the tandem-type ECRIS by using these evaporators.

Spatial Distribution of Multicharged Ions from Space Potentials Measured by Probe and Beam Methods on ECRIS

It has been performing to elucidate the basis of various physical processes, phenomena in an electron cyclotron resonance (ECR) plasma, and its various empirical methods. In order to obtain guiding principle for further improvement of the state of art technology on ECR ion source (ECRIS) will be used in various fields, the object is to develop moreover new fields together still existing applications. In this paper, spatial distribution of multicharged ions has been experimentally measured from space potential measurements with probe and beam methods, and relationship between extracted ion beam currents and other parameters has been investigated.

Spatial Variation of Electron Energy Distribution Functions along to Field Lines on ECRIS

Fundamental studies have been made to elucidate the basis of various physical processes and physical phenomena in electron cyclotron resonance (ECR) plasma. In order to obtain guiding principle for further improvement of the state of art technology on ECR ion sources (ECRIS), it is the object to develop moreover efficiencies of them in new fields together still existing applications in various field. In this paper, spatial variations of electron energy distribution function (EEDF) have been experimentally measured and reported with relationship extracted ion beam currents and other parameters.