Masaru Inoue

Shielding Effects of Superconducting YBaCuO Vessels by a Plasma Spraying Method

We have prepared shielding vessels, which has stainless steel substrates covered with YBaCuO coatings, by an atmospheric plasma spraying method. One of them have single-end open and the others double-ends open. Shielding effects inside superconducting YBaCuO vessels are measured at 77 K by a fluxgate magnetometer and a SQUID, changing applied AC fields of 10−5 T to 10−4 T and their frequencies of 0.1 Hz to 100 Hz. There is scarcely dependence on shielding effects of YBaCuO vessels for the strength and the frequency of magnetic fields examined. The field attenuation ratio is 10−6 in the center of a double-ends open vessel with a diameter of 60.5 mm and a length of 242.0 mm. For the single-end open vessel, with a diameter of 88.0 mm and a length of 176.0 mm, the field attenuation ratio is on the order of 10−5 in the portion near the bottom.

A New Superconducting Planer Magnet Development from a Magnetic Shielding Device Made of NbTi-Cu Films

We have studied the magnetizing characteristics of large scale sheets (300×1000 mm) of various tickness with superconducting NbTi-Cu multilayer films up to 100 layers in vertical magnetic field: The number of NbTi layer (n) dependence on the maximum value of trapped flux density (BTM) were investigated. In region of 0.1 µm < the thickness of a NbTi layer (d) < 1 µm at the total thickness of NbTi layers (nd)=10 µm, BTM increased in proportion to the logarithm of n value. In case of d=0.1 µm and n=100, the value of BTM was 3 times larger than that of the multilayer film with d=1.0 µm and n=10.

High Magnetic Field Shielding Devices with Superconducting NbTi-Cu Multilayer Films

We have studied the magnetic shielding effects of various hollow disks with superconducting NbTi-Cu multilayer films in vertical magnetic field. The hollow disk has an outer diameter(O.D.) of 60mm and an inner diameter(I.D.) ranging from 0 to 40mm by using the multilayer films composed of two NbTi-Cu layers which NbTi or Cu layer is 5.0um thick, respectively. As the increasing I.D. of the disks from 0 to 40mm, ΔBm (maximum magnetic shielding effects) decreased from 0.11 to 0.024-T. These studies have developed for high magnetic shielding devices which were formed by piling the hollow superconducting disks and A1 disks alternately. The device provided a space free from high magnetic field up to 0.8T.

MAGNETIC SHIELD EFFECTS OF SUPERCONDUCTING NbTi-Cu MULTI-LAYER FILMS

We have carried out the experimental study on magnetic shield effects of NbTi-Cu multilayers film deposited alternately NbTi and Cu films of various thickness. The thickness dependence of ΔBm/nd (ΔBm:max. magnetic shield effect, [d]:film thickness) with the parameter of the number of NbTi layers (n) for the multilayers film are investigated. In the region of [nd]>3μm and in any case of [n]=1,2,3,ΔBm/nd increases exponentially with decreasing [nd] and increasing [n].The relation between ΔBm/nd and [nd] is given the following formula in(ΔBm/nd)=α-βin(nd), α,β (constant). From these results, it is possible to completely seal off a magnetic field of a tesla or more by laminating NbTi-Cu multilayers film of reasonable thickness.