Takashige Shinozaki

Mechanisms of heat and oxygen transfer in silicon melt in an electromagnetic Czochralski system

Abstract The three-dimensional time-dependent flow of silicon melt in an electromagnetic Czochralski system was numerically investigated. Two different types of electrodes were used in the mathematical modeling to determine the mechanisms of heat and oxygen transfer in the melt. The results showed that electromagnetic force in the azimuthal direction suppressed natural convection due to centrifugal force. It was also shown that heat and oxygen transfer from a crucible wall to the solid–liquid interface was enhanced due to off-centered vortices.

Mechanism of Heat and Oxygen Transfer under Electromagnetic CZ Crystal Growth with Cusp-Shaped Magnetic Fields

The three-dimensional time-dependent flow of the silicon melt in an electromagnetic Czochralski (EMCZ) crystal growth system with cusp-shaped magnetic fields was numerically investigated. Calculations were carried out using five different configurations of the melt and cusp-shaped magnetic fields. The results indicated that oxygen was transferred from a part of a sidewall of the crucible on which a cusp plane of the magnetic fields exists. The results also showed that the oxygen concentration at the solid-liquid interface of silicon increased when the cusp plane of the cusp-shaped magnetic fields shifted from the bottom of the crucible to the surface of the melt.

Heat and oxygen transfer in silicon melt in an electromagnetic Czochralski system with transverse magnetic fields

Flow with three-dimensional phenomena of silicon melt in an electromagnetic Czochralski (EMCZ) system with transverse magnetic fields was numerically investigated. This paper focused on the effect of electrode positions and direction of electric current on heat and oxygen transfer in the melt. The results showed that the case with current flow perpendicular to the magnetic fields can modify heat and oxygen transfer in the melt. The results also showed that electric current flow perpendicular to the applied transverse magnetic fields enhanced heat and oxygen transfer from crucible to a crystal in the melt.

Active control of melt convection of silicon by electromagnetic force under cusp-shaped magnetic fields

Abstract Three-dimensional time-dependent flow of silicon melt in an electromagnetic Czochralski system was numerically investigated. Four different positions of electrodes were taken into account to investigate the mechanism of heat and oxygen transfer in the melt under cusp-shaped magnetic fields. The results showed that the position of electrode plays an important role to control heat and oxygen transfer in silicon melt.

A cross-spectral analysis of small voltage variation in a submarine cable between Hamada and Pusan with speed variation of the Tsushima warm current

Abstract We obtained a time series of electric voltage records by a submarine cable buried between Hamada and Pusan together with a set of speed records of the Tsushima warm current, measured southeast of the Tsushima island. A cross-spectral analysis was made between small voltage variation and speed variation. A strong correlation exists between the two variations.

Stabilization of Melt Convection of Lithium Niobate Using Accelerated Crucible Rotation Technique

The three-dimensional time-dependent flow of oxide melts in a Czochralski system using the accelerated crucible rotation technique was numerically investigated. The simultaneous effect of the double-crucible method, which enables separation of feed material and a growing crystal, on the growth of long homogeneous crystals was also investigated. Several types of crucible rotations were used to investigate the stabilization of convection of lithium niobate melt. The calculations clarified that time-dependent crucible rotation with acceleration can effectively stabilize the convection of the melt, especially in combination with the double-crucible technique.

A Simple Dynamic Calculation of Launching a Line

Abstract Using a simple model consisting of anchor, buoy, and connection, we calculate motion and tension of a line in launch. Even after the anchor has hit the bottom, the buoy keeps descending, while it loses its speed and then it stops descending to start ascending. Repeating these series of motion the buoy reaches the position of its equilibrium. We derive conditioirs under which the slack in descending motion and the overshoot in ascending motion of the line take place.

Experiments on cut ropes due to the shearing action of bodies

Abstract A mooring line was cut off in 1981 south of Tanegashima. In order to determine the cause of the accident, we prepared several artificial cut sections and compared them with the recovered one. We also made a saw type cut off experiment and obtained quantitative relations of the tension of rope, pressure of blade, and life of rope. However, we could not specify exactly what cut the mooring line.