摘要:

We describe the design, operation, and calibration of a 7.7 m DuMond geometry bent crystal spectrometer, constructed at the 184 in. Cyclotron for the study of mesonic x rays. The application of crystal diffraction techniques to mesonic x‐ray measurements is briefly discussed.

ISSN:0034-6748    

DOI:10.1063/1.1720518

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A technique has been developed for focusing a plasma beam from a coaxial accelerator which increases the plasma energy per unit area by a factor of fifteen or more without reducing the front velocity. The pressure, impulse, and power flux characteristics of a xenon plasma were measured outside the focusing device of the accelerator to optimize the operational parameters. The plasma pulse has a 107cm/sec front velocity, and sufficient cross sectional area, density, duration, and uniformity to be useful in plasma‐solid interaction studies at high power fluxes (∼45 to 100 MW/cm2), where radiation is the dominant mode of energy transfer.

ISSN:0034-6748    

DOI:10.1063/1.1720493

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A pulse generator is described for pulsing high power injection lasers at room temperature. The outstanding features of this pulser are the small size, cheapness, and simplicity, combined with the capability of switching several thousand amperes. However, the pulse repetition rate is limited to about 500 pulses/sec. The pulser may be used in optical systems where higher repetition rates are not necessary. Although this pulser was developed for pulsing injection lasers, it can also be used for all applications in need of high power pulses combined with the small size of the pulse generator.

ISSN:0034-6748    

DOI:10.1063/1.1720517

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

X‐ray production by proton bombardment was used to determine the surface density of thin films of Al, Cu, and Yb. This was accomplished by comparison at a number of thicknesses with known films. In addition, the x‐ray yield for Al was compared with values predicted by the use of x‐ray production cross section, stopping power, and bulk density. The experimental and calculated values agreed within 15%. The data are presented in linear form from 0 to 1900 Å and semilogarithmic form from 0 to 7000 Å, which is nearly a thick film for this technique. The useful upper limit lies in the range of 1000 Å for Yb and 4000 Å for Al. The lower limit is not clearly established, although the measurements for the Al surface densities were limited to surface densities equivalent to 1.2 Å as established by substrate contamination.

ISSN:0034-6748    

DOI:10.1063/1.1720519

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The electrical resistance of a manganin coil was measured at various temperatures and pressures in the ranges of 20 to 200°C and 0 to 7 kbar. Three useful results were obtained from this study. (1) At elevated temperatures, the resistance of the manganin coil is reproducible with rising and falling pressures. (2) At elevated temperatures, the resistance‐pressure curves remain linear. (3) The pressure coefficient changes only slightly with temperature. The present study indicates that the manganin coil may be used as a pressure indicator at elevated temperatures, provided that a convenient correction due to the shift of the resistance at different temperatures is made.

ISSN:0034-6748    

DOI:10.1063/1.1720520

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A modified design of a light probe with improved signal‐to‐noise ratio and reduced sample volume is described and compared to that previously discussed by J. Lee and R. S. Brodkey [Rev. Sci. Instr.34, 1086 (1963)].

ISSN:0034-6748    

DOI:10.1063/1.1720521

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A system utilizing a time averaging computer (CAT) to determine the zero crossing of the derivative of the magnetic resonance lines with an improved accuracy is described. The programming sequentially selects only the essential sections of the resonance (derivative) curve to determine the zero crossing. These are an upper off‐resonance, a near center, and a lower off‐resonance part, and the CAT accumulates these signals. Thus the resulting resolution is not limited by the fixed number of channels in the analyzer, and more data can be taken in a given experimental time. To demonstrate the system, the zero crossing of the27Al NMR line in Al metal was measured. An accuracy of the order of 1/1000 of the line width was attained, which is about 30 times better than conventional techniques.

ISSN:0034-6748    

DOI:10.1063/1.1720522

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The design of an optical system for making absolute reflectance measurements on small crystals at liquid helium and room temperature is described. The system permits accurate masking of the samples and, with only one moving component, measures reflectivity without the use of a comparison standard.

ISSN:0034-6748    

DOI:10.1063/1.1720523

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An experimental technique for impulsively loading structures by utilizing a compressed‐air gun is described. Structural models are accelerated to a prescribed velocity and stopped by impacting a long rod. Their response to the induced impulsive load is measured by high speed photographic techniques. Comparison of the theoretical and experimental response of an aluminum ring is presented and discussed.

ISSN:0034-6748    

DOI:10.1063/1.1720524

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Diamond anvils driven by a simple piston and screw device have been used to subject solid samples to pressures up to 300 kbar at ambient room temperature. Samples can be examined optically and by x‐ray diffraction while under pressure. Pressure is measured by means of the lattice parameter of sodium chloride mixed with the sample. Reflectivity and volume data on iron, as well as crystallographic data on PbS, PbSe, and PbTe, are presented.

ISSN:0034-6748    

DOI:10.1063/1.1720525

出版商:AIP    

年代:1967

数据来源: AIP