Norihide Saho

Continuous superconducting-magnet filtration system

We developed a new water purification system using a continuous superconducting-magnet filtration system that removes phytoplankton. The system consists of twin-type magnets with a helium refrigerator: a reciprocating magnetic main filter, and a rotating magnetic sub-filter. This system removes phytoplankton from lake water by separating coagulated magnetic flocks with the magnetic filters. The filters can be continuously cleaned and regenerated under low magnetic fields while flocks are being separated under high magnetic fields. This system removed more than 93% of the phytoplankton from lake water at flow rates of 400 m/sup 3//day.

Study on a mobile-type magnetic separator applying high-Tc bulk superconductors

Abstract We have developed a new water-treatment system that consists of a membrane separator and a magnetic separator that uses long high-Tc bulk superconductors (SCs) as permanent magnets. Basic tests were performed using a new prototype water-treatment system to verify the separator’s ability to remove water bloom. Based on the test results, we design the mobile-type magnetic separator system. The designed magnetic separator system consists of three components; a pre-process unit, a rotating membrane separator and a magnetic separator. The capacity of the magnetic separator is 100 ton/day. Removal rate is 90% or more. It is thought that the system is compact and high efficiency.

A Study of Magnetic Drug Delivery System Using Bulk High Temperature Superconducting Magnet

A magnetic drug delivery system (MDDS) has been studied to navigate and/or accumulate the magnetic seeded drug at a local diseased part in the human body. The bulk high temperature superconductors (HTS) are employed to control the drug because they would produce the required magnetic fields for MDDS. The trajectory of the ferromagnetic particles in the blood vessel was calculated and the possibility of the navigation of the drug is discussed. In the experiment the HTS (GdBaCuO) which produces the magnetic field of 4.5 T at the surface, was located 25 mm apart from the Y-shaped blood vessel. The drug navigation probability to the desired direction was confirmed to be higher than 80%. A rat experiment was also performed successfully using a permanent magnet. The possible MDDS system will be discussed.

Research and Development of Magnetic Drug Delivery System Using Bulk High Temperature Superconducting Magnet

The magnetic force control of the drug motion in the body has been studied in the current work. The calculation was made to study the possibility of the magnetic force control of the drag motion from outside of the body. The condition which enables the magnetic force control was clarified. The magnetic drug delivery system (MDDS) was demonstrated to be possible using the rat and permanent magnet and the validity of the calculation was confirmed by experiment. The magnetite suspension was introduced into a liver through portal vein in the rat experiment. A permanent magnet was used to navigate the magnetite. The navigation and accumulation of the magnetite was successfully performed. Based on the results, the MDDS experiment was made with an HTS magnet for a large-sized animal, pig. The HTS magnet of which size was 45 mm in diameter and 90 mm in length produced 5 T at 38 K. The suspension of the magnetite was injected into the blood vessel of the pig. It was confirmed that the magnetite was successfully navigated and/or accumulated by the HTS magnet.

Magnetization method for long high-T/sub c/ bulk superconductors used for magnetic separation

We have developed a new water-treatment system consisting of a membrane separator and a magnetic separator that uses long (>200 mm) high-temperature bulk superconductors (SCs) as permanent magnets. For magnetizing the long bulk SCs, we developed a new magnetization method. Namely, a field is applied, the bulk SCs are cooled below their transition temperature (T/sub c/), and during cooling, the bulk SCs are inserted into and withdrawn from the applied field repeatedly. As a result, the bulk SCs experience high and low fields under a gradually cooled ambient, and the trapped field gradually increases. The benefit of this method is that it can magnetize large bulk SCs by using a small field magnet. We fabricated an embedded-SC bulk magnet more than 200-mm long, and magnetized it by split-solenoid superconducting magnets with a diameter of approximately 100 mm. Field measurements showed that the developed method can magnetize a wider area over the bulk SCs than that possible with a conventional field-cooling method.

Cryostat and nuclear magnetic resonance imaging apparatus including a cryostat

A magnetically shielded cryostat, e.g. in a MRI imaging apparatus, has a heat-insulating tank having an outer wall. A magnetic shield is spaced from the tank, covers at least partly the outer wall of the tank and is not supported by the tank. A refrigerator having a cooled member extends into the tank. In order to avoid direct transmission of vibration of the refrigerator to a center region of the shield, the refrigerator is supported on the magnetic shield by at least one elongate support member connected to the shield only at or close to the ends of the shield.

MONTE CARLO SIMULATION OF TRANSMISSION PROBABILITY IN CRYOPUMPS FOR NEUTRAL BEAM INJECTORS

Neutral Beam Injector (NBI) with negative ion source is under development as one of the most promising heating devices for achieving the objective plasma parameters in the Large Helical Device (LHD) at NIFS. This paper considers the development of high speed cryopumps for the NBI in the LHD. A new type of louvre blind cryopump having parallel 80 K louvre blinds and 3.7K cryopanels, located parallel to the 80 K louvre blinds, is proposed. At the ratios of B/C = 0.92 and D/B = 1.2, the transmission probability of this advanced type is calculated to be 0.72 which means the cryopump system with this louvre blind type can theoretically attain a high pumping speed.

DEVELOPMENT OF A PARALLEL-LOUVRE-BLIND TYPE CRYOPUMP FOR FUSION REACTORS

As a new type of actual sized cryopump with high pumping speed, a parallellouvre-blind type cryopump of a rectangular cross section with opening distance B, width C and depth D, is proposed and is produced as a trial pump unit designed to actual size. The influence of pump depth size ratio Rd(=D/B) and number of secondary cryopanels on the transmission probability Pbc of the pump unit is calculated by Monte Carlo simulation and the hydrogen pumping speed is measured by experiments. The following results are obtained: (1) The transmission probability of a cryopump designed with dimensional ratio of Rd=1.3, is calculated to be 0.66 at ratios of Rc(=B/C)=0.88, which means that hydrogen pumping speed of this sized cryopumps can attain 294m3s−1/m2per opening area. (2)The experimental hydrogen pumping speed of the trial pump unit with 29 secondary cryopanels, is measured to be 295m3s−1/m2.

Pumping Speed of Parallel-Louvre-Blind-Type Cryopumps. Hydrogen Pumping Speed of Cryopump with Multiple Parallel Mounted Panels.

As a new type of actual-sized cryopump with high pumping speed, a parallel-louvre-blind type cryopump of a rectangular cross section with opening distance B, width C and depth D, is proposed and is produced as a trial pump unit designed as actual size. The influence of pump depth size ratio Rd(=D/B) and number of secondary cryopanels on the transmission Probability Pbc of the pump unit is calculated by Monte Carlo simulation, and the hydrogen pumping speed is measured by experiments. The following results are obtained. (1) The transmission probability of a cryopump designed with dimensional ratio of Rd=1.3 is calculated to be 0.66 at ratios of Rc(=β/C)=0.88, which means that hydrogen pumping speed of cryopumps of this size can attain 294 m3·s-1/m2 per opening area. (2) The real hydrogen pumping speed of the trial pump unit with 30 secondary cryopanels is measured as 295m3·s-1/m2.

Pumping Speed of Parallel-Louvre-Blind-Type Cryopump. Transmission Probability of Cryopump with Multiple Parallel-Mounted Panels.

As a new type of louvre blind cryopump, a parallel-louvre-blind cryopump with a rectangular chamber with opening distance B, louvre width C and depth D, is proposed. The influence of louvre size ratio Rc(=B/C) and pump depth size ratio Rd(=D/B) on the transmission probability Pbc is calculated by the Monte Carlo simulation and measured in model experiments. The following results are obtained. (1) The transmission probability of a cryopump designed with a dimensional ratio of Rd=1.28, is calculated as 0.7 at ratios of RC=0.7∼0.9, which means that this type of cryopump can theoretically atttain a high pumping speed of more than 300 m3·s-1/m2 per opening area. (2) The transmission probability of the cryopump strongly depends on Rd and decreases rapidly for Rd less than 1.0 in the case of Rc=0.92.