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.
HTS magnets: stability; protection; cryogenics; economics; current stability/protection activities at FBML☆
Abstract The unique features that distinguish a high-temperature superconducting (HTS) magnet from a low-temperature superconducting (LTS) magnet are: (1) operating temperature and (2) temperature span over which the magnet remains superconducting. Thus, for two magnets, one HTS and the other LTS, both satisfying the same set of field specifications, the operating temperature and the operating range of temperature of the HTS magnet are generally an order of magnitude greater than that of the LTS magnet. In this CHATS 2002 Workshop, four issues, i.e., stability, protection, cryogenics, and economic issues will be examined as they are impacted by the two unique features, first as a general introduction to this presentation, between HTS and LTS magnets. This is followed by discussion of economics of large-scale HTS devices, specifically of fusion; electric power devices; high-energy physics; research-purpose NMR; and high- B DC magnets. The paper concludes with a presentation of preliminary results of stability/protection research presently being performed at the FBML.
An analytical approach to the design of electrodes in high-power, fast-transverse-flow CO2 lasers
Abstract Usually, the design of the electrodes of fast-transverse-flow CO 2 lasers relies more on experimental data than on theoretical analysis. Traditional systems sustain a stable, high-power discharge but the current distribution generates a peaked, non-uniform small-signal-gain pattern. We present a theoretical model suitable for the design of electrodes that achieves a quasi uniform gain distribution. The analysis, based on a two-temperature model and the gas-transport equations, computes the electron density that supports a flat gain pattern. Combining the desired electron density with the electron-balance equations, the model determines the required electric field. The results were used to design a new set of electrodes for a home-made fast transverse flow CO 2 laser. A stable, large volume discharge ( 4 × 8 × 90 cm 3 ) with very good uniformity was obtained. The resulting gain distribution was registered in a bi-dimensional map. The peak gain rose from 1.2 m - 1 , attained with the old electrode set, to 1.6 m - 1 with the new one and the gain showed a homogeneous profile.