Theoretical Analysis and Design Consideration of Advanced Linear Type Magnetic Flux Pump
As a current compensator, we already developed a linear type magnetic flux pump (LTMFP) that is comprised of DC coils, three phase armature coils, an LTS Nb foil and laminated linear slots. The LTMFP produced a homopolar traveling magnetic field with DC bias current and 3-phase armature current and then, a pumping current is generated in the closed superconducting loop. In this study, we have proposed an advanced LTMFP which can easily produce homopolar traveling magnetic field with the combination of a permanent magnet and the AC armature current. Since the permanent magnets have replaced DC coils in the system, its structure and operation are simplified. As well as, the heating loss of the advanced LTMFP is reduced due to the permanent magnet compared with the LTMFP. From this reason, we confirmed that the advanced LTMFP has more simplified and efficient operation compared with already developed magnetic flux pumps. This paper describes the structure and operating principle of the advanced LTMFP. As well as, the distributions of electromagnetic-thermal analysis of the LTS Nb foil were calculated based on the finite element method (FEM). Thus, in order to realize the homopolar traveling magnetic field, appropriately designing parameters of the combination of AC current and the permanent magnet were obtained.
Linear Flux Pump Device Applied to High Temperature Superconducting (HTS) Magnets
This paper presents a novel linear flux pump which could be used to magnetize 2G HTS tapes and coils. The design is based on an iron magnetic circuit together with copper solenoids and is powered by a current source driver circuit. Several applied waveforms were tested including a symmetric sine wave and an asymmetric trapezoidal wave. Both standing and travelling waves were applied. The measurements focused on the effects of frequency and magnitude of the applied field and their effect on the system pumping efficiency. It was found that a trapezoidal wave was more effective than a sine wave, producing a greater final current at the same applied frequency and field strength. The maximum induced current in the superconducting coil was 19 A which was achieved using an applied field of 50 mT, applied as a travelling trapezoidal wave. The driving current to the copper coils was 5 A in amplitude with a frequency of 10 Hz. It was found that when the applied field magnitude was less than 16 mT pumping did not occur. It proved possible to pump the system with a standing wave as well as a travelling wave. This effect needs to be investigated further as it is possible that the standing wave had travelling components.
Pioneer 10 Observations of the Ultraviolet Glow in the Vicinity of Jupiter
A two-channel ultraviolet photometer aboard Pioneer 10 has made several observations of the ultraviolet glow in the wavelength range from 170 to 1400 angstroms in the vicinity of Jupiter. Preliminary results indicate a Jovian hydrogen (1216 angstrom) glow with a brightness of about 1000 rayleighs and a helium (584 angstrom) glow with a brightness of about 10 to 20 rayleighs. In addition, Jupiter appears to have an extensive hydrogen torus surrounding it in the orbital plane of Io. The mean diameter of the torus is about equal to the diameter of the orbit of Io. Several observations of the Galilean satellites have also occurred but only a rather striking Io observation has been analyzed to date. If the observed Io glow is predominantly that of Lyman-α, the surface brightness is about 10,000 rayleighs.