Current axial

Dehberate stirring can be imposed on conductors with a transverse rotating magnetic field or by passage of electric current axially with a transverse magnetic field. Conversely, a constant magnetic field with no current imposed greatly reduces natural convection. 

Lock, C.M. Dyer, E. Characterization of High Pressure Quadrupole Collision Cells Possessing Direct Current Axial Fields. Rapid Commun. Mass Spectrom. 1999,75,432-448. 

Lock, C. M. and Dyer, E. (1999) Characterisation of high pressure quadrupole collision cells possessing direct current axial fields. Rapid Commun. Mass Spectrom., 13,432-48. Thomson, B. A. and Jolliffe, C. L. (1998) Spectrometer with axial field. U.S. patent 5,847,386. Javahery, G. and Thomson, B. (1997) A segmented radiofrequency-only quadrupole collision cell for measurements of ion collision cross section on a triple quadrupole mass spectrometer. J. Am. Soc. Mass Spectrom., 8, 697-702. 

At this time the NICMOS schedule calls for launch and insertion into HST in May of 1997. Decisions on which of the current axial HST instruments NICMOS will replace will be based on the status and utilization of the current instruments approximately 1 to 2 years before launch. NICMOS is currently under construction at Ball Aerospace, with several of the key dewar components already completed. The design and developmoit of NICMOS is complete although the detailed filter compliment and grism parameters are stiU under evaluation. All NICMOS flight detector arrays are due for delivery by the end of 1994. There will be a total of three primary and six spare arrays. All nine arrays will meet flight specifications, but the three primary arrays will be chosen based on the qualification data and further... 

Current histogram of cumulated AE events vs axial position, for each monitored component. 

There are difficulties of detecting defects in axial canal because of solid sediment layer of 1. 2 mm thick on the canal surface. When using known defectoscope devices a preliminary labor-intensive mechanical treatment of the axial canal surface is needed. The experience of application of different methods of rotor axial canal control in multifunction automatic device ROTOR - K has pointed to the fact that the most effective method is eddy current one [1]. All the dangerous cracks were just detected by the eddy current method, the part of the cracks were not... 

In order to solve the problem of detect control of axial canal without preliminary surface clearing, the eddy-current transformer with operating butt end... 

Assuming that the current in the gas is carried mostly by electrons, the induced electric field uB causes transverse electron motion (electron drift), which, being itself orthogonal to the magnetic field, induces an axial electric field, known as the Hall field, and an axial body force, F, given by... 

This simplified discussion has neglected the effects of axial current flow, ie. Hall current, induced by the axial field. At a local region in the channel, equation 1 can be written in more general form as... 

There are four basic variations of the linear MHD channel (Fig. 5) which differ primarily in their method of electrical loading. The simplest is the two-terrninal Faraday or continuous electrode generator, Figure 5a, where a single pair of current-collecting electrodes spans the channel in the axial direction, short-circuiting the channel from end to end. Hence, for this configuration, = 0, andj can be obtained from equations 21 and 22 ... 

Additionally, there exists an axial or Had current j given by... 

Compared to the expression of equation 5, having no axial current flow, power output is reduced by the factor 1/(1 + /5 ). This is because part of the kinetic and thermal energy of the gas generates the axial current j which flows upstream in the gas and returns through the electrode wads. This current does not flow through the external load and so represents a loss. 

In practice, elimination of axial current flow requires relatively fine segmentation, eg, 1—2 cm, between electrodes, which means that a utihty-sized generator contains several hundred electrode pairs. Thus, one of the costs paid for the increased performance is the larger number of components and increased mechanical complexity compared to the two-terrninal Faraday generator. Another cost is incurred by the increased complexity of power collection, in that outputs from several hundred terminals at different potentials must be consoHdated into one set of terminals, either at an inverter or at the power grid. 

Another configuration having power collection from only two terminals is the Hall generator shown in Figure 5d. In this configuration, opposing electrode pairs are connected, and the current flow for power extraction is axial. E = 0, and... 

The resulting overall energy balance for the plant at nominal load conditions is shown in Table 3. The primary combustor operates at 760 kPa (7.5 atm) pressure the equivalence ratio is 0.9 the heat loss is about 3.5%. The channel operates in the subsonic mode, in a peak magnetic field of 6 T. AH critical electrical and gas dynamic operating parameters of the channel are within prescribed constraints the magnetic field and electrical loading are tailored to limit the maximum axial electrical field to 2 kV/m, the transverse current density to 0.9 A/cm , and the Hall parameter to 4. The diffuser pressure recovery factor is 0.6. 

Cathode and insulator walls are less subject to severe electrochemical attack. In the case of the cathode wall, this is because of the reducing conditions which prevail, and in the case of the insulator wall, because the wall nominally carries no current. However, certain surfaces of cathode and insulator walls are anodic with respect to other surfaces, because of the axial electric field present in the generator, and these surfaces do require protection against electrochemical attack. 

Data are not currently available on the dispersion with the newer fluidfoil impellers, but they are often used in industrial mixer-settler systems to maintain dispersion when additional resonance time holdup is required, after an initial dispersion is made by a radial- or axial-flow turbine. 

Dispersion Model An impulse input to a stream flowing through a vessel may spread axially because of a combination of molecular diffusion and eddy currents that together are called dispersion. Mathematically, the process can be represented by Fick s equation with a dispersion coefficient replacing the diffusion coefficient. The dispersion coefficient is associated with a linear dimension L and a linear velocity in the Peclet number, Pe = uL/D. In plug flow, = 0 and Pe oq and in a CSTR, oa and Pe = 0. 

An active magnetic axial bearing consists of two stators and a rotor disk (Figure 6-4). A sensor located at the end of the shaft monitors and maintains the rotor position between the two stators. The principle of operation is the same for both axial and radial bearings any deviation from the normal position of the rotor is communicated to the electronic control system, which adjusts the electric current going to the electromagnets to correct the rotor position. 

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