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Several research and developments have been performed at a compact ECR ion source (Kei3) with a fixed magnetic field at HIMAC. The Kei3 is a testing machine for application of Kei series developed for high-energy carbon-ion radiotherapy. It is difficult for Kei3 to produce ions that are heavier than carbon ion because it uses the same magnetic field distribution as the Kei series. In order to improve the beam current of multiply charged ions such as the neon and the argon, the two microwave frequency heating method was tested in Kei3. Microwaves are introduced from the vacuum box on the upstream side of the plasma chamber through the rectangular waveguide of the WR-90. A traveling wave tube (TWT) amplifier made by NEC (LD79X75A1) is used as the microwave source. The frequency band is 9.75-10.25 GHz and the maximum output power is 750 W. The WR-75 waveguide is also introduced from the upper part of the upstream vacuum box and installed on top of the existing WR-90 waveguide. A TWT amplifier manufactured by Xicom (XTRD-300IJ) was used as a microwave source for the two frequency heating. The frequency band is 10-18 GHz and the maximum output power is 300 W. A beam test with oxygen, neon, and argon was performed in order to confirm the effect of two microwave frequency heating. In this test, we focused on O6+, Ne7+, and Ar9+ ions. We checked the microwave frequency at the XTRD-300IJ, dependence of the microwave power at the LD79X75A1 and charge state distributions of O, Ne and Ar.

Several research and developments have been performed at a compact ECR ion source (Kei3) with a fixed magnetic field at HIMAC. The Kei3 is a testing machine for application of Kei series developed for high-energy carbon-ion radiotherapy. It is difficult for Kei3 to produce ions that are heavier than carbon ion because it uses the same magnetic field distribution as the Kei series. In order to improve the beam current of multiply charged ions such as neon and argon, the two-microwave-frequency heating method was tested in the Kei3. Microwaves are introduced into the plasma chamber with a WR-90 rectangular waveguide. A traveling wave tube (TWT) amplifier made by the NEC (LD79X75A1) is used as the microwave source. The frequency band is 9.75-10.25 GHz and the maximum output power is 750 W. The WR-75 waveguide is also introduced from the upper part of the upstream vacuum chamber and installed on top of the existing the WR-90 waveguide. A TWT amplifier manufactured by the Xicom (XTRD-300IJ) was used as a microwave source for the two-microwave-frequency heating. The frequency band is 10-18 GHz and the maximum output power is 300 W. A beam test with oxygen, neon, and argon was performed in order to confirm the effect of two microwave frequency heating. In this test, we focused on O6+, Ne7+, and Ar9+ ions. We measured the dependence of the XTRD-300IJ microwave frequency and the microwave power of the LD79X75A1 on a charge state distributions.

Electron cyclotron resonance ion sources (ECRISs) are widely applied for ion beam applications, e.g., plasma processing, cancer therapy, and ion engine of an artificial satellite. In our ECRIS, we aim at producing and extracting various ion beams from this device, in particular, Xeq+ ion beams at low energy. In the aerospace engineering field, there are problems of accumulated damages on various component materials caused by low energy of Xe ions from the engine. There are not enough experimental sputtering data for satellite materials at the Xeq+ in the low energy region. Then, we are trying to investigate the sputtering yield experimentally by irradiating the low energy Xe ion beams. To perform this experiment, it is necessary to acquire a certain amount of beam current with low energy. Then, we generate the low energy ion beams by the following steps: First, the ion beams are extracted from the ECRIS at high voltage. Next, these are transported to an ion beam irradiation system (IBIS). Finally, the ion beams are decelerated by the deceleration voltage in the IBIS. We adjusted the beamline. We measure the characteristics of the transport efficiency and decelerated ion beam currents. In this paper, we describe the experimental setup using an existing ECRIS for decelerated heavy ion beams and the results of decelerated ion beam currents.

We have considered the accessibility condition of electromagnetic and electrostatic waves propagating in an electron cyclotron resonance (ECR) ion source (ECRIS) plasma and then investigated experimentally their correspondence relationships with production of multicharged ions. It has been clarified that there exists an efficient configuration of ECR zones for producing multicharged ion beams and has been suggested that a new resonance, i.e., upper hybrid resonance (UHR), must have occurred. We have been trying to perform advanced experiments with 4–6 GHz X-mode microwaves to the 2.45 GHz ECRIS plasma, and we have succeeded in enhancing the production of multicharged ions by launching X-mode microwaves of these bands. Furthermore, at the same time, we have observed sharp increases in electron energy distribution functions in the ECRIS plasma by means of probe methods. It has been concluded that the UHRs must have occurred when applying multiplex microwaves with their frequencies away from those frequencies for ECR in the ECRIS. In this paper, we will describe in brief the theoretical background and the results of these new experiments.We have considered the accessibility condition of electromagnetic and electrostatic waves propagating in an electron cyclotron resonance (ECR) ion source (ECRIS) plasma and then investigated experimentally their correspondence relationships with production of multicharged ions. It has been clarified that there exists an efficient configuration of ECR zones for producing multicharged ion beams and has been suggested that a new resonance, i.e., upper hybrid resonance (UHR), must have occurred. We have been trying to perform advanced experiments with 4–6 GHz X-mode microwaves to the 2.45 GHz ECRIS plasma, and we have succeeded in enhancing the production of multicharged ions by launching X-mode microwaves of these bands. Furthermore, at the same time, we have observed sharp increases in electron energy distribution functions in the ECRIS plasma by means of probe methods. It has been concluded that the UHRs must have occurred when applying multiplex microwaves with their frequencies away from those frequencie...

An electron cyclotron resonance (ECR) ion source (ECRIS) can generate an available amount of multicharged ions, thus it is not limited for use in the field of accelerator science, but also in medical/biological fields, such as for heavy ion beam cancer treatment and ion engines. The processes of generating multicharged ions are mainly sequential collisions of a direct ionization process by electrons, and have good ion confinement characteristics. By utilizing this confinement property, we have synthesized iron-encapsulated fullerenes, which are supramolecular and can be expected to have various high functions. Fullerenes and iron ions are vaporized from pure solid materials and introduced into the ECRIS together with the support gas. We investigated conditions under which fullerene ions do not dissociate and iron ions are generated so that both can coexist. Generated ions are extracted from the ECRIS and separated by mass/charge with a dipole magnet, and detected with a Faraday cup. This measurement system is characterized by a wide dynamic range. The charge-state distribution (CSD) of ion currents was measured to investigate the optimum conditions for supramolecular synthesis. As a result, a significant spectrum suggesting the possibility of iron-encapsulated fullerenes was obtained. This paper describes the details of these experimental results.

We insert two probes in the upstream and the downstream regions with respect to the electron cyclotron resonance (ECR) zone which is formed at the center of mirror fields. We measure simultaneously plasma parameters in those regions by each of them under the same operating condition. We measure ion saturation currents Iis and electron energy distribution functions at two positions. We obtain measurement results that suggest the more efficient ECR on the side closer to the microwave-launchings than those on the other side. It is consistent with the accessibility condition of the right-hand polarization wave. We also compare the charge state distributions of Ar ion beams extracted in the case of launching microwaves from the coaxial semi-dipole antenna and those from the rod antenna. We observe the higher multicharged ion beam currents at the low microwave powers in the case of the rod antenna than those in the case of the coaxial semi-dipole antenna. We also confirm stable increasements of ion beam currents at considerably high microwave powers in the case of the coaxial semi-dipole antenna. Based on the experimental results, we propose a new microwave-launching method, "dual-ECR heating" and report its preferable preliminary experimental results in this paper.

How to produce multicharged ions efficiently on an electron cyclotron resonance ion source (ECRIS) has been investigated at Osaka University. Notably, in recent years, we have focused on heating by new resonance superimposing to electron cyclotron resonance (ECR) plasma. To evaluate its efficiency, we need to know the maximum efficiency of heating with ECR alone, and then, further optimization of ECR heating is required. In consideration of wave propagation, we installed the coaxial semi-dipole antenna on the mirror end along the geometrical axis of the vacuum chamber. We aim at exciting the strength of right-hand polarization (RHP) waves for efficient ECR because RHP waves give rise to ECR. We measure plasma parameters by Langmuir probes and charge state distributions (CSDs) of the extracted ion beams and investigate their qualitative tendencies to incident microwave powers and pressures. We compare the qualitative trend of ion beams and their CSD on microwave power in the case of both the microwave feeding system by the coaxial semi-dipole antenna and that by the rod antenna. Differences between the microwave feeding system before improving and then after upgrading are made clear.

Electron cyclotron resonance ion sources (ECRISs) are used in various fields such as accelerator physics, engineering, cancer therapy, and ion engines in the satellite. We are aiming to improve the production of multicharged ions efficiently at the point of view from the length of multipole magnets and vacuum conditions in the ECRIS. The diameter of the connection pipe between the main chamber and diffusion pump was made larger to improve vacuum conductance. Moreover, the length of multipole magnets with the direction along the geometrical axis in the ECRIS was extended. The effects of these improvements are investigated experimentally to measure the pressure in the vacuum chamber, beam intensity, charge state distributions of extracted ion beams, and plasma parameters. The purity of extracted ion beams and magnetic confinement have been enhanced. These results are expected to have positive effects on the production of various species and synthesized ion beams, e.g., production of iron endohedral fullerene in the future experiments in the ECRIS.