Takuya Nishiokada

New tandem type ion source based on electron cyclotron resonance for universal source of synthesized ion beams.

A new tandem type source has been constructed on the basis of electron cyclotron resonance (ECR) plasma for producing synthesized ion beams. We investigate feasibility and hope to realize the device which has wide range operation window in a single device to produce many kinds of ion beams based on ECR ion source (ECRIS). It is considered that ECR plasmas are necessary to be available to individual operations with different plasma parameters. Both of analysis of ion beams and investigation of plasma parameters are conducted on produced plasmas. We describe construction 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.

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.

Plasma potential measurement on ECRIS by using extracted ion beam

With the miniaturization of semiconductors, the technology of shallow junctions becomes important. As shallow junctions advance, ion implantation by using ion beams at low energy with good control is needed. An electron cyclotron resonance ion source (ECRIS) can efficiently generate a high-density plasma at low pressure and a high intensity ion beam. In our ECRIS, the wide operation of various ion beam is available from deeper implantation of multi-charged ions at high energy to shallow junction at very low energy. However, a potential and a sheath near the wall are formed with an ECR plasma, because ECRIS is a volume source. Therefore, the potential affects the control of the ion beam at very low energy. In this study, we measure the potential by using the ion beam extracted from the ECRIS. In addition, we confirm that the potential by using the ion beam method correlates with electron temperature when microwave power and pressure change in ECRIS.

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.

Effect of mid-electrode potential on multi-charged ion beam extracted from electron cyclotron resonance ion source

We are constructing a tandem type electron cyclotron resonance ion source (ECRIS) and a beam line for extracting, analyzing ion beams, and their applications. The ion beam is extracted from the second stage by an accel-decel extraction system with single-holes and the ion beam current on each electrode is measured. The total ion beam current is measured by a faraday cup installed at downstream from the extraction electrodes. The ion beam current of each charge state is measured by the faraday cup beyond the sector magnet. The most of the total ion beam is consisted of mainly Ar+ ~ 4+ and we can measure up to Ar9+. We measure the total ion beam current and the currents of each charge state as a function of the mid-electrode potential. It is found that the ion current of each charge state depends on the same manner to the mid-electrode potential as similar to the total ion beam currents. The results obtained experimentally against the mid-electrode potential show qualitatively good agreement with a simple theoretical consideration including sheath potential effects for formation of ion beams. The beam loss is estimated by comparing the total ion beam currents with the sum of the currents after mass/charge analysis. The effect of mid-electrode potential is very useful for decreasing the beam loss and then optimizing beam transport for enhancing ion beam current extracted from tandem type ECRIS with many ion sources.

Improved ion production and extraction on tandem type ECRIS with low magnetic mirror field

A tandem-type electron cyclotron resonance (ECR) ion source (ECRIS) has been constructed for synthesizing, extracting, and analyzing ions. The feasibility and realization of the device which has rangy operation window in a single device are investigated to produce many kinds of ion beams like universal source based on ECRIS. The ECR plasmas are considered to be necessary to be available to coexist and to be operated individually with different plasma parameters. Both of analysis of ion beams and investigation of plasma parameters will be conducted on produced plasmas. In this article the experimental study concentrates on improvement of producing and extracting multicharged ion beams from the second stage of the tandem-type ECRIS under lower magnetic mirror field with octupole magnets. The assembly of the extractor is modified and their positions, gap, and potentials are investigated against each ion spices. We succeeded in producing, extracting multicharged ion currents and improving ion extraction, while the magnetic field is about 60% of the previous magnetic field strength. We will present obtained evidences experimentally in detail.

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.