Rotation Of Permanent Magnets Research Articles

Synthesizing an algorithm to control the angular motion of spacecraft equipped with an aeromagnetic deorbiting system

It is known that the synthesis of the relevant control law is performed and appropriate control devices are selected for specific tasks of controlling relative spacecraft motion. Flywheels, control moment gyroscopes, electromagnetic devices with permanent magnets and micro-jet engines are used as actuators in controlling the orientation and stabilizing the spacecraft. For example, flywheel motors together with electromagnets are most often used to ensure precise spacecraft stabilization in remote Earth monitoring (REM) problems. At the same time, there is a series of problems pertaining to the control over the relative motion of spacecraft where there is no need for precise spacecraft stabilization and ensuring minimal errors in orientation. These problems may include spacecraft orientation for charging solar batteries or orientation control for research and meteorological spacecraft.The study's purpose is to synthesize a law for spacecraft orientation control algorithm when using executive devices with permanent magnets (EDPM). EDPMs are the devices controlling spacecraft orientation. They consist of rotary permanent magnets, stepper motors, and capsule-screens with shutter flaps. Opening and closure of the capsule-screen flaps and rotation of permanent magnets in a certain way ensure the generation of a discrete control magnetic moment. It should be noted that EDPMs do not provide accurate spacecraft stabilization and hence they are not suitable for the REM purpose. However, EDPMs consume less on-board energy than other spacecraft orientation control systems and are useful in problems requiring less accurate stabilization.A control law was synthesized for controlling spacecraft equipped with EDPM using a nonlinear controller and a pulse-width modulator. Areas of effective EDPM application for various space-related problems including orientation and stabilization of aerodynamic elements perpendicular to the dynamic flow of the incoming atmosphere were determined. Advantages of using EDPMs in comparison with electromagnetic executive devices in the problems pertaining aerodynamic element stabilization in aerodynamic systems of deorbiting worked-out spacecraft from low Earth orbits were shown.

Design of a Compact and Multi-Function Magnetic Field Steered Arc Source

Based on the principle of the control of magnetic field on arc spot motion, a compact and multi-function magnetic field steered arc source has been designed in this paper. The rotating magnetic field generator driven by small DC motors or AC motors has been also equipped behind the base of the target materials of magnetic field steered arc source. The magnet yoke fixed on shaft will be driven by the motors so as to promote the rotation of permanent magnets which are rationally distributed on magnet yoke. The different distribution of permanent magnets will produce the rotating magnetic field with different configuration structures and then the purpose of multi-control mode can be achieved. Meanwhile, the dynamic rotating magnetic field with different configurations have been also produced in this design through employing the simple and compact arc source as well as the permanent magnet with different distributions in order to improve the discharge form of arc spots, control the trajectory of arc spots, improve the utilization of target materials and the uniformity of etching as well as reduce or inhibit the emission of large particles. At the same time, the high-quality film can be also prepared so as to realize the arc spot control with various forms in an arc source, satisfy the different demands and expand the application of arc ion plating.

A study on a magnetic separation of radioactive corrosion products from NPP using permanent magnets

It is important to emphasize that the current trend to longer fuel cycles (18–24 months) has complicated the dilemma of finding optimum chemical condition for the primary coolant because of some problems such as increase of radioactive corrosion products, possibility of axial offset anomaly and so on. Radioactive corrosion products which are generated by the neutron activation of general corrosion products at a nuclear power plant are the major source of occupational radiation exposure. Generally, radioactive corrosion products exit in soluble and insoluble forms, and are removed by ion exchangers and purification filters. Most of the insoluble radioactive corrosion products have the characteristic of showing strong ferrimagnetism. Along with the new development and production of permanent magnets (rare earth magnets) which generate much stronger magnetic fields than conventional permanent magnets, a new type of magnetic filter is suggested that can efficiently separate corrosion products using rotation of permanent magnets. This new magnetic filter reveals good performance results in filtering magnetite, cobalt ferrite and nickel ferrite from aqueous coolant simulation.

Construction of electromagnetic rotation sensor using compound magnetic wire and measurement at extremely low frequency rotations

A pulse generator device, utilizing the effect of large Barkhausen jumps, is investigated. The device is an assembly of rotating permanent magnets and a magnetic sensing element. The sensing element is a compound magnetic wire around which a search coil is wound. The compound magnetic wire is made by twisting a ferromagnetic wire and is doubly layered. The surface shell part of the wire has lower coercivity compared to the inner core part. Even if the frequency of the external field due to the rotation of permanent magnet becomes nearly zero, we observe the sharp voltage pulse of 2 mV/turn due to a large Barkhausen jump. We demonstrate an impeller type flowmeter as an application of these experimental results, which is able to detect 0.5 l/min, where the rotation speed is so slow that the impeller is stopping due to the friction. >