Magnetization filters

Magnetic filters have been used to clean paint sHps and Hquids. Filters that are open to the atmosphere or closed, ie, pressure type, are available where the filter inlets are matched to standard pipe connections from 10 to 50 mm, for low capacity appHcations. 

Filter selection, based on the feed capacity, m /h, to be handled, varies from 1 to 45 m /h in the many sizes available. A permanent magnetic filter is shown in Figure 11. 

Filter elements may be of the 5-micron, woven mesh, micronic, porous metal, or magnetic type. The micronic and 5-micron elements have non-cleanable filter media and are disposed of when they are removed. Porous metal, woven mesh and magnetic filter elements are usually designed to be cleaned and reused. 

Aixiang Wei, DUm Chen, Ning Ke, Shaoqi Peng, S. P. Wong, Characteristics of Carbon Nitride Eilms Prepared by Magnetic Filtered Plasma Stream, Thin Solid Films, Vol. 323, No. 1-2,1998,pp.217-221. 

For a nuclide of mass M, abundance sensitivity is the ratio between the signal at mass M+ arising from the same species to the signal at mass M. Off-peak ions are present because of collisions behind the magnetic filter, of reflections on the tube wall, or of space-charge effects. As a result of the collisions, the energy of these ions is different from the energy of the main beam. They alter the apparent peak baseline in a continuous way. Abundance sensitivity decreases with the mean free path of ions, i.e., when pressure near the collector assembly... 

To construct the magnetic filtration set up, the magnetic filter is installed in a conduit system through which buffer is pumped by means of a peristaltic pump (Fig. 1). 

Position the magnetic filter device(s) in the 3 mm-gap between the two pole faces of the electromagnet. 

Through each magnetic filter 0.75 mL of the sample is pumped at a rate of 12 mL/h. 

Magnetic filter may cut pollution, Chem. Ecology, p.ll, July (1980). 

Fig. 7.1.2 A magnetization filter blocks part of the incoming magnetization from passing through the filter.

A magnetization filter consists of modulated rf excitation, for example, from a sequence of nonselective rf pulses with given flip angles and given pulse separations. These parameters of the pulse sequence are adjustable, and they determine the characteristics of the filter, that is, they can be used to tune the filter transfer function. Therefore, they are referred to as extrinsic contrast parameters. They must be discriminated from the intrinsic contrast parameters, which are the NMR parameters specific of the sample under investigation and are related to the material properties [Manl]. Therefore, the parameter vectorp in the weight factor of eqn (7.1.2) is separated into two parts, a vector Pe of extrinsic parameters and a vectorPj(r) of intrinsic parameters. 

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