Axial Extraction Research Articles

MHD flow distortion caused by strong Hall effect

A tensor conducting steady gas flow penetrating a spatially increasing applied magnetic field is considered. The gas is taken to be compressible, inviscid and with a constant fractional ionization. It is shown that a rotational mass motion will be imparted to the flow because of the Hall effect. The rotation is estimated to be large, especially for strong magnetic fields and light gases with a fractional ionization of more than 10-4. MHD power generation aspects of this phenomenon are discussed and expected to be serious for generators with axial power extraction because the distorted pressure distribution will have a short-circuiting action on the axial Hall field.

Axial mixing and extraction in a mechanically agitated liquid extraction tower

AbstractAxial mixing was measured in both phases for a countercurrently operated, mechanically agitated extractor of the Oldshue‐Rushton design for water continuous and toluene and kerosene dispersed. Results in terms of an eddy axial diffusivity were correlated in terms of the variables studied. These correlations were then applied to column performance during extraction of n‐butyl amine from kerosene into water, and the true mass transfer coefficients, corrected for axial mixing, were determined. These are shown to be predictable for droplets of dispersed phase considered to be rigid spheres.

Analysis of linear mhd power generators

The finite electrode size effects on the performance of an infinitely long MHD power generation duct are calculated by means of conformal mapping. The general conformal transformation is deduced and applied in a graphic way. The analysis includes variations in the segmentation degree, the Hall parameter of the gas and the electrode-insulator length ratio as well as the influence of the external circuitry and loading. A general criterion for a minimum of the generator internal resistance is given. The same criterion gives the conditions for the occurrence of internal current leakage between adjacent electrodes. It is also shown that the highest power output at a prescribed efficiency is always obtained when the current is made to flow between exactly opposed electrodes. Curves are presented showing the power-efficiency relations and other generator properties as depending on the segmentation degree and the Hall parameter in the cases of axial and transverse power extraction. The implications of limiting the current to flow between a finite number of identical electrodes are introduced and combined with the condition for current flow between opposed electrodes. The characteristics of generators with one or a few external loads can then be determined completely and examples are given in a table. It is shown that the performance of such generators must not necessarily be inferior to that of segmented generators with many independent loads.

A High Current Radio Frequency Proton Source with Radial Extraction

A theory outlining the mechanism of the low pressure hydrogen plasma used in radio frequency proton sources is given. Taking into account secondary emission from surfaces of plasma vessel it is shown that the electron density is maximum at the tube's center. This is confirmed experimentally, and a source is designed with its extraction electrode positioned radially near the plasma center. Compared with axial extraction used in conventional r.f. sources, radial extraction yields beam currents over 20% higher, and allows the application of higher extraction voltages. Beam currents up to 150 Ma. can be extracted, of which more than 85%, is proton current. Two methods are used for the measurement of the emittance of the accelerated beam.

Axial mixing and extraction efficiency

AbstractThe effect of back mixing of either phase in an extraction column, which decreases the extraction efficiency, is analyzed theoretically by means of an idealized diffusion model that can be characterized by four dimensionless parameters: a Peclet number of each phase, a mass transfer number, and the usual extraction factor. Calculations for a wide range of these parameters were performed on a digital computer.The principal results, presented in a table, will be useful in the design and scale up of extraction columns and in the interpretation of experimental results from extractors and from some reactors in which a first‐order reaction occurs.

Ion source for radioisotope separation

An ion source of the oscillating electron type with axial magnetic field and end extraction has been constructed for electromagnetic separation of synchrocyclotron-produced radioactive isotopes. A description of the ion source and the results of some systematic investigations of its properties are given. The performance of the ion source is illustrated by some recent applications to prepare sources for spallation studies and nuclear spectroscopy.

A High-Intensity Pulsed Ion Source

A pulsed cold cathode ion source, giving peak proton currents in excess of one milliampere and average currents up to 50 microamperes, is described. The source is based on the Penning discharge using axial extraction of the ions. Some discussion of the discharge mechanism and the role of the cathode material is included. Installation and operation of this source in the Berkeley 4-mv Van de Graaff and its performance in that machine is discussed.