摘要:

A three component, wind tunnel balance capable of magnetically suspending a test model in the center of a 25 cm diameter, high velocity, low density gas stream without the use of mechanical supports has been developed. Reaction forces experienced by the model are resolved into three mutually orthogonal components with one of these components being aligned with the axis of the tunnel. A complete description of the magnetic and electrical components of the balance is presented.

ISSN:0034-6748    

DOI:10.1063/1.1720073

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A mechanical device for obtaining fluorescence spectra is described. The elimination of the exciting radiation and stray light in this device is highly effective, so that very weak fluorescence signals can be recorded without optical filters.

ISSN:0034-6748    

DOI:10.1063/1.1720074

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A new technique, called ``identical area microscopy,'' allows direct comparison of the results of optical, electron probe, and electron microscope studies of the same area. Although the contamination film which builds up on a specimen during electron probe studies can adversely influence analysis, it proves to be an excellent surface replica for electron microscope studies.

ISSN:0034-6748    

DOI:10.1063/1.1720075

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Low pressure measurements by Bayard‐Alpert gauges are limited by x‐ray photoelectric currents at the ion collector, equivalent to a pressure reading of about 1×10−11Torr. Through efforts to reduce this x‐ray current, the Bayard‐Alpert structure has been modified, whereby a beam of ions is extracted from the grid and bent around a corner to a remote collector. By this geometry the collector is shielded from the x‐ray source at the grid, and the photoelectric current is reduced by a factor of 100, without incurring a loss in gauge sensitivity. Bending of the ion beam is accomplished by a cylindrical, electrostatic field, in which the ion trajectories are independent ofe/m. 100% modulation of the ion beam intensity is achieved by turning off the bending field, thereby permitting pressure measurements as low as 1×10−14Torr. A total pressure of 5×10−13Torr, nitrogen equivalent, has been measured in a stainless steel vacuum system employing ion sputtering and titanium sublimation as the means of evacuation.

ISSN:0034-6748    

DOI:10.1063/1.1720076

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A different approach has been developed to measure two‐body collision cross sections in the energy range from thermal to several hundred electron volts. Two molecular beams are merged and move in the same direction along a common axis. Ion‐neutral reactions are discussed but the techniques could also be used for ion‐ion and neutral‐neutral collisions. Advantages of the merging beams technique over conventional beam‐gas and crossed beam methods include accessibility (with good energy resolution) to the energy region from a few tenths of one to a few electron volts; the possibility of measuring cross sections for two general, labile species; and relative ease in collecting and detecting products for total reaction cross section measurements. The principles of the method and details of the instrument are discussed. A cross section for the resonant charge transfer of Ar was measured. Reasonable agreement with some previous measurements, and other tests, indicate that the basic principles of a merging beams technique are valid and that the apparatus performs satisfactorily.

ISSN:0034-6748    

DOI:10.1063/1.1720077

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A dielectric cell with platinum electrodes fused onto concentric glass cylinders is described. The cell is completely shielded and of the three terminal, guarded type necessary for the precise measurement of dielectric constants and conductances without the use of reference liquids. It can be cleaned readily with strong oxidizing agents, can be dried and filled with electrodes in place, and can be thermostated with relative ease. Another feature of the cell is its ease of construction and its adaptability to the rapid measurement of dipole moments and conductances in solutions of very low dielectric constant.

ISSN:0034-6748    

DOI:10.1063/1.1720078

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The scarcity of accurate bulk modulus data on many liquids led to the construction of an apparatus to determine both adiabatic and isothermal bulk modulus values. The apparatus is designed for highly compressible liquids such as pentane as well as relatively ``hard'' liquids like water or crude oils. The temperature range of the instrument is from 0 to +50°C, and the pressure range from 0 to 300 kg/cm2. The precision in adiabatic bulk modulus measurements with this apparatus has been determined for water for which the derived error is 0.1%.

ISSN:0034-6748    

DOI:10.1063/1.1720079

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A thin 2 mm liquid hydrogen target is described. It operates at conditions away from the boiling curve and can therefore absorb considerable (200 mW) power from an accelerator beam without serious boiling. Construction and operation are discussed and several additional advantages are presented.

ISSN:0034-6748    

DOI:10.1063/1.1720080

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A transducer system is described which enables the transverse frequency of resonance of strings to be determined with great precision. The theoretical discussion enables the magnitude of the output to be calculated, and a practical system used by the author is given. The excitation and detection of movement of the fiber is purely electrical, depending on the fact that a charged fiber vibrating with a small amplitude between two electrodes causes a charge movement at the electrode proportional to its displacement.

ISSN:0034-6748    

DOI:10.1063/1.1720081

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A superconducting switch is described which has an electrical resistance of 45 &OHgr; in the nonsuperconducting state. The dimensions of the switch are 3.5×3.5×1.5 cm.

ISSN:0034-6748    

DOI:10.1063/1.1720082

出版商:AIP    

年代:1966

数据来源: AIP