Magnetic assembly

For general-purpose use below 1000 Hz, a transducer can be attached to a machine by a magnetic base. Even though the resonant frequency of the transducer/magnet assembly may distort the data, this technique can be used with some success. However, since the magnet can be placed anywhere on the machine, it is difficult to guarantee that the exact location and orientation is maintained with each measurement. Shows common magnetic mounts for transducers. 

A most recent commercial Nano Indenter (Nano Indenter XP (MTS, 2001)) consists of three major components [66] the indenter head, an optical/atomic force microscope, and x-y-z motorized precision table for positioning and transporting the sample between the optical microscopy and indenter (Fig. 28). The load on the indenter is generated using a voice coil in permanent magnet assembly, attached to the top of the indenter column. The displacement of the indenter is measured using a three plate capacitive displacement sensor. At the bottom of the indenter rod, a three-sided... 

T. Miyamoto, H. Sakurai, H. Takabaya-shi, M. Aoki 1989, (A development of a permanent magnet assembly for MRI devices using Nd-Fe-B material), IEEE Trans. Magn. 25, 3907-3909. 

In our final realization (Fig. 18), the probes use the Helmholtz coil geometry, favoring ease of use and efficient sample temperature control over a wide range of temperature values. The tunable, broad-band probe is inserted into the magnet from below and fixed to the bottom part of the magnet assembly in a simple way reminiscent of most high-resolution NMR systems. Thanks to this design, it is possible to use standard 10 mm NMR sample tubes which are inserted comfortably from above without any need to manipulate the probe. 

Magnet Assembly. Several types of magnet assemblies and pole combinations have been used successfully. Both electro and permanent magnet assemblies have also been employed. The permanent assembly is frequendy preferred because of the power savings effected. Typical pole specifications for the various applications are five or six poles for cobbers as well as for roughers, and from four to ten (normally five) poles for finishers. 

From memory, draw a cutaway diagram of a superconducting magnet assembly (including the probe). Describe the purpose of each part of the assembly. 

A Raman spectrometer instrument compatible with the assay format, consisting of an optical system and sample tube holder was developed in house. The sample holder includes a magnetic assembly that produces a focused magnetic field at a precise location on the wall of the sample tube. This location is coincident with... 

Magnetically coupled drive mechanisms have a set of inner magnets located atop the impeller shaft that extends down into the pressure vessel. This inner magnet assembly is positioned so that it can be rotated within and be encapsulated by a small pressure vessel chamber. This chamber is made of nonmagnetic material and is attached and sealed to the head of the reactor vessel. This chamber is then surrounded by another set of matching magnets located in an... 

Suspended Magnet. In this case, the magnet assembly includes a permanent magnetic core surrounded by a belt conveyor, lire suspended magnet configuration is either cross-belt or in-line, with respect to the waste material flow (Figure 19). 

The gradient coils are inserted inside the room temperature shim coils in the magnet (Fig. 2.3.1). Depending on the type of spectrometer, they can be part of the magnet assembly or part of the removable probe assembly. The former are typical for medical... 

Yoo B, Rheem Y, Beyermann WP, Myung NV (2006) Magnetically assembled 30 nm diameter nickel nanowire with ferromagnetic electrodes. Nanotechnology 17 2512-2517... 

Figure 3.3. Floor vibrations can introduce unwelcome artefacts around the base of a resonance (a) which can be largely suppressed by mounting the magnet assembly on an anti-vibration stand (b) (figure courtesy of Bruker).

In many locations it is advantageous to mount the whole of the magnet assembly on a vibration damping system as floor vibrations (which may arise from a whole host of sources including natural floor resonances, air conditioners, movement in the laboratory and so on) can have deleterious effects on spectra, notably around the base of resonances (Fig. 3.3). Whilst such artefacts have lesser significance to routine ID observations, they may severely interfere with the detection of signals present at low levels, for example those in heteronuclear correlation or nuclear Overhauser effect experiments. 

Take out the upper part of the commercial internal NMR magnet assembly, including the spinner turbine. 

---