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.
Characteristics of Contactless Power Transfer for HTS Coil Based on Electromagnetic Resonance Coupling
This paper describes a operating characteristics of contactless power transfer (CPT) system from normal conducting coil to HTS coil based on the electromagnet resonance coupling. The basic principle is that two separate coils with same resonance frequency are possible to form a resonant system based on high frequency magnetic coupling and exchange energy in a high efficiency. The CPT technique with the electromagnetic resonance coupling has been expected as a useful option for contactless charge and storage devices. Since the CPT technology using normal conducting coils is sensitive to tune impedance matching, the transfer power efficiency is limited. From this reason, we proposed the combination CPT technology with superconducting receiver coils, it is called as, superconducting contactless power transfer (SUCPT). The SUCPT system can reduce joint loss of superconducting connection and increase the portability of the superconducting system. In this study, as a fundamental step, the optimal power transfer conditions needed to generate inductive power transfer between normal conducting coils and superconducting coil were experimentally examined. The power transfer profile for coupled resonance coils with high frequency power was investigated in order to minimize operating power.
VLA stereoscopy of solar active regions. 2: Altitude, relative motion, and center-to-limb darkening of 20 centimeter emission
A newly developed method of stereoscopic correlation is applied to solar radio maps at a wavelength of 20 cm. On the basis of stereoscopic correlations between radio maps obtained on 6 different days we establish the presence of 66 radio source components associated with 22 active regions. We find the following statistical results for active region source structures at 20 cm: 1. The observed lifetime is consistent with an exponential distribution having an e-folding time scale of greater than 18 days. 2. The average altitude of 20 cm sources is 25 +/- 15 Mm; 90% of the sources are found in heights less than 40 Mm. 3. The average diameter of discrete source structures is 48 +/- 15 Mm, implying a vertical/horizontal aspect ratio of q(sub A) approx. = 0.5. 4. No significant source motion has been found with respect to the standard differential rotation rate of Omega = 13.45 deg - ((3 deg (sin(exp 2)B)). 5. We find a statistical limb darkening, which can be described by the relation (T(sub B)(alpha))/T(sub B)(0)) = 0.4 + ((0.6(cos(exp 2) alpha)) for sources with T(sub B) greater than 0.5 MK. 6. The degree of source polarization is 15% +/- 10% and is independent of source location. 7. Bright sources (greater than or approximately equal to 0.5 MK), or equivalently, long-lived sources (greater than or approximately equal to 5 days) show a systematic variation of their altitude as function of the center-limb distance.