Takuto Watanabe

Broad Ion Beam Extraction from Large Bore ECR Ion Source with Cylindrically Comb‐Shaped Magnetic Fields Configuration by Feeding Simultaneously 11 to 13 GHz and 2.45 GHz Microwaves

We tried to enlarge the operation window of an electron cyclotron resonance (ECR) ion source for producing the ECR plasma confined by cylindrically comb‐shaped magnetic field, and for extracting the broad ion beam under the low pressures and low microwave powers. The magnetic field by permanent magnets constructs ECR zones at different positions for 2.45 GHz and 11 to 13 GHz microwaves, respectively. According to probe measurements, profiles of plasma density and temperature are different for using each single microwave. We conduct production of ECR plasma by launching simultaneously these two frequency microwaves, and obtain flat profiles of the electron density and the electron temperature. These profiles are not achieved by feeding single frequency microwave. It is found that plasma can be controllable on spatial profiles beyond wide operation window of plasma parameters. We conducted preliminary extracting and forming large bore ion beam from this source. We will make this source a part of tandem type...

Ion Beam Extraction from Large Bore 11 to 13 GHz ECR Ion Source with a Pair of Cylindrically Comb‐Shaped Magnetic Fields

We have developed a large bore electron cyclotron resonance (ECR) ion source with cylindrically comb‐shaped magnetic field configuration to realize high current density and comparatively large bore ion beam which can be used for beam processes under low pressure and low microwave power. It is found that the plasma confinement of cylindrically comb‐shaped magnetic fields is more effective than that of simple multipole magnetic fields. We have constructed a large bore ion beam extractor and set to the ECR ion source. The electron density attained to 1017∼18 m−3 order, ion saturation current density is about 80∼100 A/m2 under low pressure 0.03 Pa and low microwave power 200 W. We conduct the first trial of ion beam extraction from the ECR ion source. We investigate the ion beam characteristics for extraction voltages and Ar gas pressures. The extracted ion beam current increases in proportion to extraction voltages, however at present the beam current is lower than those estimated from ion saturation current...

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.

Pure Material Vapor Source by Induction Heating Evaporator for an Electron Cyclotron Resonance Ion Source

Multiply charged iron ions are produced from solid pure material in an electron cyclotron resonance (ECR) ion source. We develop an evaporator by using induction heating with the induction coil which is made from bare molybdenum wire and surrounding the pure iron rod. We optimize the shape of induction heating coil and operation of rf power supply. We conduct experiment to investigate reproducibility and stability in the operation and heating efficiency. Induction heating evaporator produces pure material vapor, because materials directly heated by eddy currents have non‐contact with insulated materials which are impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10−4 to 10−3 Pa. We measure temperature of iron rod and film deposition rate by depositing iron vapor to crystal oscillator. We confirm stability and reproducibility of evaporator enough to conduct experiment in ECR ion source. We c...