Yasuhiro Fuwa

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In this paper, we propose a new resource allocation scheme that enhances a diversity effect with taking into account a proportional fairness (PF) in downlink MIMO-OFDMA-CDM (multiple input multiple output - orthogonal frequency division multiple access - code division multiplexing) systems. In the proposed scheme, spectral resources are allocated per(More)
The gliding locomotion is defined as forward motion by the difference of friction between normal direction and tangential direction. Unlike conventional propulsion, the gliding locomotion method can move on low friction surface. Gliding locomotion robots have a simple mechanism, but it is difficult to control these robots. In previous researches, many(More)
A new set of vanes of radio frequency quadrupole (RFQ) accelerator was commissioned using highly charged iron beam. To supply high intensity heavy ion beams to the RFQ, direct plasma injection scheme (DPIS) with a confinement solenoid was adopted. One of the difficulties to utilize the combination of DPIS and a solenoid field is a complexity of electro(More)
In Brookhaven National Laboratory, laser ion source has been developed to provide heavy ion beams by using plasma generation with 1064 nm Nd:YAG laser irradiation onto solid targets. The laser energy is transferred to the target material and creates a crater on the surface. However, only the partial material can be turned into plasma state and the other(More)
To investigate efficient graphite material for carbon ion production in laser ion source, the plasma properties produced from these materials are measured. Comparing acquired current profile and charge state distribution, the distributions of ions in laser induced plasma from isotropic graphite and single crystal of graphite are different. The produced(More)
To create mixed species ion beam with laser pulses, we investigated charge state distributions of plasma formed from both Al-Fe alloy targets and pure Al and Fe targets placed close together. With two targets, we observed that the two kinds of atoms were mixed when the interval of two laser pulses was large enough (40 μs). On the other hand, when the(More)
Multiple laser shots could be used to elongate an ion beam pulse width or to intensify beam current from laser ion sources. In order to confirm the feasibility of the multiple shot scheme, we investigated the properties of plasmas produced by double laser shots. We found that when the interval of the laser shots is shorter than 10 μs, the ion current(More)
Compact H(+) ECR ion source using permanent magnets is under development. Switching the hydrogen gas flow in pulse operations can reduce the gas loads to vacuum evacuation systems. A specially designed piezo gas valve chops the gas flow quickly. A 6 GHz ECR ion source equipped with the piezo gas valve is tested. The gas flow was measured by a fast ion gauge(More)
A magnetic field can increase an ion current of a laser ablation plasma and is expected to control the change of the plasma ion current. However, the magnetic field can also make some fluctuations of the plasma and the effect on the beam emittance and the emission surface is not clear. To investigate the effect of a magnetic field, we extracted the ion(More)