Katsuhiko Kasuya

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Force-balanced coil (FBC) is a helically wound hybrid coil of toroidal field coils and a solenoid. The FBC can significantly reduce the required mass of the structure for induced electromagnetic forces. Based on the FBC design, a superconducting model coil has been developed. The outer diameter of the model FBC is 0.53 m. The model FBC will have 270 kJ(More)
A superconducting force-balanced coil (FBC), which is geometrically one tenth the size of a 100 MJ class SMES coil, has been developed. The FBC is a helically wound hybrid coil of toroidal field coils and a solenoid. This coil configuration can minimize the required mass of the structure for induced electromagnetic forces. The model FBC with an outer(More)
A computer model for calculating screw compressor performance is presented. Geometrical characteristics such as volume curve, sealing line length, discharge port area, etc. are studied. The volume curve is obtained from the sealing line shape, using the principle of virtual work. This procedure has the advantage of simplifying the numerical calculation of(More)
A one tenth sized model coil based on the force-balanced coil (FBC) design for 100-MJ class SMES has been designed. This coil is a hand-made coil using NbTi superconductors, and the winding of the model FBC is now in progress. The FBC is a helically wound hybrid coil of toroidal field coils and a solenoid. This coil can minimize the mechanical stress and(More)
Recent work on pulsed cryogenic ion sources at the Tokyo Institute of Technology are reviewed briefly. Surface flashover processes of low-temperature dielectric materials are investigated experimentally in connection with the cryogenic ion sources. Values of dc or pulse breakdown voltage are measured, and fast-frame photographs are taken to observe the(More)
Laser-based diagnostic methods are developed to improve our understanding of the behavior of flashover-type magnetically-insulated diodes. For the quantitative estimation of the particle density, a resonant interferometric and a laser resonance scattering method are developed. These techniques could allow direct determination of the particle distribution in(More)
Pulsed ion beams are extracted from two kinds of inverse reflex tetrodes, and their characteristics are investigated in detail. When the size of the tetrode is enlarged and a triple point is formed on the beam side, extracted beam currents are doubled. Current neutralized proton beams with a peak energy of 180 keV are obtained with the extraction angle of(More)
A magnetically insulated diode with a cryogenically refrigerated anode is proposed for the first time and a prototype of such a diode is constructed. H2O ice is produced on an anode which is cooled with liquid nitrogen. A small machine fed with a marx generator and a blumlein line is used to extract ion beams. Proton beams of about 50 A and 70 keV are(More)
To bunch the beams, we need (1) focusing type Ion diode without turn-on delay times etc., and (2) large current channels to transport focused ion beams. In these regards, we operated a pulsed ion source with a so called active anode, and we designed a small channel to be assembled together with our cryogenic ion diode to prepare future experiments.
The potentiality of surface flashover plasma produced from condensed materials is tested as a negative ion source of hydrogen. A coaxial magnetically insulated diode, whose cathode can be cooled by liquid nitrogen or liquid helium, is driven with a 5-Ohm/60nsec Blumlein line. The experimental results confirm the source effect on the negative ion generation.(More)