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We have designed and fabricated micromechanical magnetometers intended for a 3D electronic compass which could be embedded in portable devices. The sensors are based on the Lorentz force acting on a current-carrying coil, processed on a single crystal silicon resonator, and they are operated in vacuum to reach high enough Q values. Sensors for all cartesian components of the magnetic field vector can be processed on the same chip. The vibration amplitude is detected capacitively and the resonance is tracked by a phase-locked-loop circuit. The fabrication process is based on aligned direct bonding of a double side polished silicon wafer and a SOI wafer. Magnetometers measuring the field component along the chip surface have a flux density resolution of about 10 nT/√Hz at a coil current of 100 μA. Magnetometers measuring the field component perpendicular to the chip surface are currently less sensitive with a flux density resolution of about 70 nT/√Hz. The standard deviation of the signal was less than 1% over a period of a few days.

We have designed and fabricated micromechanical magnetometers intended for a 3D electronic compass which could be embedded in portable devices. The sensors are based on the Lorentz force acting on a current-carrying coil, processed on a single crystal silicon resonator. Sensors for all cartesian components of the magnetic field vector can be processed on the same chip. The vibration amplitude is detected capacitively and the resonance is tracked by a phase-locked-loop circuit. The fabrication process is based on aligned direct bonding of a double side polished and a SOI wafer. Magnetometers measuring the field component along the chip surface have a flux density resolution of about 10 nT/√Hz at a coil current of 100 μA. Magnetometers measuring the field component perpendicular to the chip surface are currently less sensitive with flux density resolution of about 70 nT/√Hz. Resolution is limited by the fundamental thermomechanical noise. The standard deviation of the signal was less than 1% over a period of 5 days.

A hybrid undulator for generation of high brilliance synchrotron radiation in the photon energy range of 60–600 eV at the 550 MeV electron storage ring MAX in Lund, Sweden has been designed and built at the Technical Research Centre of Finland in close collaboration with MAX‐lab of Lund University. At the rather modest electron energy of MAX this photon energy range can be reached only by an undulator featuring a fairly short period and the smallest possible magnetic gap. Even then, higher harmonics (up to the 13th) of the radiation spectrum must be utilized. An optimization of the magnetic design resulted in a hybrid configuration of NdFeB magnets and soft iron poles with a period of 24 mm and a minimum magnetic gap of 7–10 mm. A variable‐gap vacuum chamber allows reduction of the vacuum gap from a maximum of 20 mm, needed for injection, down to 6 mm during stored beam operation. A special design of this chamber permits a magnetic gap between pole tips that is only 1 mm larger than the vacuum gap. Adequa...

In collaboration with VTT Automation, Euroshield Inc - one of the leading European manufactures of electrically and magnetically shielded enclosures - has developed a new cost-effective magnetic shielding concept. For a typical enclosure size of 3 m x 4 m x 2.5 m the shielding factor exceeds 60 dB at low frequencies and rises above 90 dB at frequencies beyond 10 Hz. This concept, which is based on two passive aluminium+mumetal shielding structures. For the passive shield, a new modular assembly technique has been developed and the pneumatically operated door gives and almost seamless wall surface in the closed position. In the active stage the demagnetizing coils installed in the passive shielding are used a noise filed sensors. In this way no external sensor are needed, a large number of signal are available for optimization of the shielding performance and a natural integration of spatially in homogeneous noise fields, corresponding to the shape of the shield, can be utilized.

Research and development, manufacturing and industrial applications of magnetic separation in Finland are reviewed.

An undulator operating at radiation wavelengths between 250 and 2000 A has been constructed at the Technical Research Centre of Finland and recently installed at the MAX storage ring in Lund. The undulator utilizes ferrite permanent magnets in the hybrid configuration. The magnetic and mechanical design, calculated performance and influence on the electron beam of the undulator are discussed.

The design and optimization of short period (λu l 20 mm) undulators is discussed. It is shown that such undulators are preferably realized by permanent magnet arrays in the hybrid configuration. Evaluation of the magnetic field of the hybrid configuration by the scalar potential method is reviewed and useful approximations for the short period region are derived.