摘要:

A mass spectrometer has been utilized to study the gas composition during operation of a CO2laser using a BeO waveguide. The results indicate that the use of a drying agent to absorb water vapor has allowed us to achieve lifetimes in excess of 5000 h in sealed waveguide lasers.

ISSN:0034-6748    

DOI:10.1063/1.1136482

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In addition to the deflection of the charged particles during their passage through an electrostatic deflector, it is proposed to impose a gradual retardation along their path, so that they leave the instrument at lower energy. By means of a new figure of merit involving the usual optical characteristics (dispersion, aberration, and magnification), it is shown that this principle can improve the performances of electron spectrometers, taking the 127° cylindrical electrostatic analyzer as an example. Calculations of energy transmission functions show that, at constant energy resolution, an increase of about 100% in the transmitted intensity may be expected for a retardation factor of 10. Further considerations on the space charge in a monochromator show that, since the charge density is mainly concentrated at the entrance and relatively unaffected by the retardation, the principle could be efficient for electron monochromators, too.

ISSN:0034-6748    

DOI:10.1063/1.1136483

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The design of an air‐cored electomagnetic coil system is a very specific problem because of one essential feature: every characteristic parameter of the field produced is mainly determined by the geometry of the current‐bearing conductors. Various methods are presented to overcome the mathematical and computational difficulty of homogeneity optimization. Linearization of the field equations allows solving them with a pocket calculator, with some significant design restrictions. Nonlinear resolution and full system simulation can be performed at a computer center or on a scientifically‐oriented microcomputer system, both possibilities having their own advantages and tradeoffs. As an example, the optimization of a whole‐body NMR imaging magnet is presented. Compensation of field inhomogeneities up to the 14thorder allows a drastic reduction of magnet size and power consumption. A sketch of the procedures and results at three different levels—pocket calculator, microcomputer, and computer center—is presented.

ISSN:0034-6748    

DOI:10.1063/1.1136484

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We present the design of a versatile rf heterodyne spectrometer covering a 100 kHz to 190 MHz frequency range, which has been useful in nuclear magnetic resonance and acoustic experiments over its whole range. Commercial instruments were used wherever possible: two units, an rf pulse generator, and a 30‐MHz IF amplifier/detector were constructed and are described in detail. Also, we briefly outline application to ultrasound and NMR measurements and interfacing to a minicomputer‐based data processing system.

ISSN:0034-6748    

DOI:10.1063/1.1136485

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The implementation of the dynamic emittance matching (DEM) concept into our secondary ion mass spectrometer is described. The importance of this feature is presented in terms of increased ion transmission when operating at low primary ion beam fluxes, that is, the static secondary ion mass spectrometry (SIMS) or molecular SIMS mode. A discussion of the principle and the design of the DEM electronics in the system is given. Experimental comparisons are presented and discussed which contrast DEM and conventional results with respect to viewing area, ion transmission, and imaging capability.

ISSN:0034-6748    

DOI:10.1063/1.1136486

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An instrument to mass spectrometrically analyze volatile compounds trapped or formed in an intractable solid matrix such as a polymer or resin‐fiber composite is described. Samples are precisely abraded inside the ion‐source housing of a time‐of‐flight mass spectrometer, and the evolved compounds are mass analyzed. By use of appropriate data acquisition and analysis techniques, either qualitative or quantitative information about the indigenous volatile compounds can be obtained. In the latter case, distribution profiles of the trapped compound(s) can be measured. Typical results for water in an epoxy resin and the pertinent experimental variables in obtaining accurate distribution profiles are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1136487

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A versatile system for measuring the thermal expansion and the magnetostriction of spherical samples has been developed. A diaphragm sensor was constructed for measuring changes in strain (&Dgr;l/l0) in the range 10−3–10−6. A strain gauge technique is used where the change in length of the sample is determined by measuring the deformation of a membrane. A linear correlation between the change of length and the output signal of the sensor is shown. The temperature dependent calibration function is determined by a data processing system. The device is calibrated by using the known thermal expansion of Ni and Al in the temperature range 80–300 K. The correct operation of this technique is verified by measuring the thermal expansion of Cu and Nb. In addition the thermal expansion of Tb, Dy, TbCo2, and DyCo2have been obtained and the results are in good agreement with published data.

ISSN:0034-6748    

DOI:10.1063/1.1136488

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Experimental methods are presented for the measurement of mass density and electrical conductivity of liquids. Density is measured by a new thermometrical method using a resistive detector, and conductivity by a standard four probe method. An application is given to tellurium and density–conductivity data are obtained in the temperature range of 450°–800°C and the pressure range of 30–1500 bars.

ISSN:0034-6748    

DOI:10.1063/1.1136464

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A simple and noninvasive technique is demonstrated for measuring the plasma electrical impedance for a class of reactors commonly used in fabricating integrated circuits. These reactors have an adjustable electrical matching network for optimizing the power transfer into the plasma. A procedure for determining in the matching network the needed values of components, which are normally difficult to measure directly, is also developed and illustrated. This dynamic measurement of plasma impedance, when combined with an electrical model of the plasma, is shown to be useful for monitoring the electron density and the electron‐neutral collision frequency in the process plasma.

ISSN:0034-6748    

DOI:10.1063/1.1136465

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An instrument for remote observation of cloud physical properties was designed and fabricated. As part of a larger payload, it was tested in a series of aircraft flights on the NASA CV‐990 in the summer of 1976 and the NASA WB‐57F in the summer of 1979. The instrument is a scanning radiometer with six channels in the near infrared and one channel in the thermal infrared. The optical techniques employed, and the mechanical and electrical design implementation of the instrument, are described. Early results of the data gathered using this instrument are presented to indicate the instrument performance.

ISSN:0034-6748    

DOI:10.1063/1.1136466

出版商:AIP    

年代:1981

数据来源: AIP