摘要:

Some early studies of the pinch effect, made with a view to its application to the problem of developing a thermonuclear reaction are here presented, together with experimental arrangements for producing pinched discharges in toroidal and straight discharge tubes. Dynamical properties of the pinch and its instabilities are demonstrated, and the possibility of stabilizing the latter is mentioned.

ISSN:0021-8979    

DOI:10.1063/1.1722792

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The dependence of ultrasonic attenuation and velocity on plastic deformation in 2Saluminum is compared at two frequencies, five and ten megacycles, and the comparison shows agreement as regards frequency dependence with what one can expect from dislocation damping theory.

ISSN:0021-8979    

DOI:10.1063/1.1722793

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Measurements have been made of the energy distribution of electrons penetrating thin samples of Al2O3. The observations were made using a 127° electrostatic analyzer. These results allow a determination of the dissipation of electron energy with depth when 2.5–10 kev electrons strike Al2O3. Results obtained indicate that for a given bombarding energy the average energy loss per unit thicknessdW/dxremains almost constant over the entire penetration depth. However,dW/dxdecreases slowly as the bombarding electron energy increases. These observations are in general agreement with those made by Ehrenberg and Franks for 10–40 kev electrons striking phosphors.

ISSN:0021-8979    

DOI:10.1063/1.1722794

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Deformation twins related to two separate (111) orientations have been observed in a copper single crystal deformed by tensile extension at 4.2°K. The unambiguous determination of the twin relationships is accomplished by a unique x‐ray technique which makes use of a single crystal adapter and Geiger counter methods. The adapter permits the detection and measurement of weakly diffracting reflections and the twin relationships are established by the unique application of geometrical data in a stereographic projection.

ISSN:0021-8979    

DOI:10.1063/1.1722795

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A method has been developed for obtaining apermanentthree‐dimensional view of the flux pattern of a magnetic field by suspending microscopic magnetically‐responsive particles in a transparent plastic solution, applying the magnetic force to form the particles into a definitive pattern of the field, and allowing the plastic to set. After the plastic solidifies, the specimen may be cut and polished for observation and later study or reference. A variation of this technique provides for the preparation of views on transparent plates. The process lends itself readily to the study and resolution of problems in magnetics encountered in research and development. It also has possible applications in the fabrication of magnetic and electronic components.

ISSN:0021-8979    

DOI:10.1063/1.1722796

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A simplified method of calculating the crystallographic features of a diffusionless (martensitic) phase change is described and applied to the gold‐cadmium alloy cubic‐orthorhombic transformation. Use of the method requires a knowledge of the initial and final crystal structures and the specification of the crystallographic plane and direction of the inhomogeneous shear. It is based on the requirement that after partial transformation the interface between the two phases be free from stress on a macroscopic scale. The method involves representing on a stereographic net (a) the loci of directions in the original phase unchanged in length by the structure changeper seand (b) the loci of directions unchanged in length by the inhomogeneous shear. The intersection of these loci determine possible undistorted interface planes. Excellent agreement with experimental observations is found when the method is applied to the cubic‐orthorhombic transformation in gold‐cadmium alloys.

ISSN:0021-8979    

DOI:10.1063/1.1722797

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Plastic deformation may be introduced in LiF single crystals by abrading, quenching, or bending. For x‐ray wavelengths of about 1.5 AU(CuK&agr;) the diffracting power is increased about 4 times by any of the three methods. For shorter wavelengths of about 0.7 au(MoK&agr;) the increase in diffracting power is about 4, 7, and 10 times for abrading, quenching, and bending, respectively. The bent crystals are more effective at shorter wavelengths because the plastic deformation is more uniform throughout the crystal while in the abraded crystal, all the deformation is concentrated in a layer extending only 0.002 inch below the surface. The extent and concentration of plastic deformation is shown by selective etching of dislocation sites.

ISSN:0021-8979    

DOI:10.1063/1.1722798

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The concentration dependence of the residual resistivity of Ni&sngbnd;Pd alloys might be expected to obey a simple Nordheim law since the number of holes in thedband and the number of electrons in thesband are approximately independent of composition. Measurements have indicated, however, that the maximum resistivity occurs at 70 atomic percent Pd instead of 50%. This behavior can be explained by the spin dependence of electron scattering processes associated with the fact that the alloys with greater than 3% Ni are ferromagnetic. Quantitative fit of the data is possible if it is assumed that the density of states at the Fermi energy in thedband is approximately proportional to the number of holes, rather than to the cube root of this number. Data on the resistivity and paramagnetic susceptibility of Ag&sngbnd;Pd alloys support this hypothesis. The relative strength ofs‐dscattering tos‐sscattering must be assumed to be about 5:1.

ISSN:0021-8979    

DOI:10.1063/1.1722799

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The long‐wave spectrum of a neutron beam from the Be reflector of the Materials Testing Reactor (MTR) has been measured from 3 A to 10 A by a total reflection technique. The spectrum was found to vary as &lgr;−3.9.

ISSN:0021-8979    

DOI:10.1063/1.1722800

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Magnetic domain patterns have been observed on evaporated films of iron, cobalt, nickel, and several different alloys of these elements. The films were deposited in the presence of a magnetic field to establish a uniaxial direction of easy magnetization. It was found that the direction of easy magnetization, in films of all compositions, could be changed by re‐heat‐treating them in a magnetic field with a new orientation. This is of special interest because bulk specimens of the elements do not respond to heat treatment in a magnetic field. Nucleation and growth of domains were observed for fields applied at various angles to the uniaxial direction of easy magnetization in some of the films. Patterns were obtained on films ranging in thickness from approximately 50 A to 12 000 A. Domain walls in films ranging from 50 A to 500 A in thickness tend to aggregate in pairs.

ISSN:0021-8979    

DOI:10.1063/1.1722801

出版商:AIP    

年代:1957

数据来源: AIP