摘要:

A simple, low‐cost conductance bridge circuit, which provides high‐resolution measurements ofdI/dVandd2I/dV2for a voltage‐biased load, is presented. A resolution indI/dVfor a 90‐&OHgr; tunnel junction of several parts in 105has been measured using a 35‐&mgr;V‐rms modulation level and a 1‐s postdetection time constant (Bn=0.25 Hz). The output impedance of the voltage source and the error in the conductance measurement are discussed. The output impedance of the circuit with an AD119 operational amplifier is 0.02 &OHgr;. A detailed discussion of Johnson‐Nyquist, tunnel junction, and amplifier noise is presented.

ISSN:0034-6748    

DOI:10.1063/1.1135947

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A method for continuous mass spectrometric analysis of high‐temperature reacting gas mixtures is described. The apparatus consists of a unique combination of three devices: the shock tube, the time‐of‐flight mass spectrometer, and the supersonic molecular beam. The driven section of the shock tube constitutes the reservoir of a supersonic molecular beam by which gas is continuously extracted from the reaction zone and introduced through a two‐stage high‐capacity vacuum system into the ionization region of the mass spectrometer. The shock tube and the mass spectrometer are coupled at right angles to one another. This configuration avoids excessive pressure buildup in the mass spectrometer system. The apparatus has an estimated mass resolution of 100 amu, a frequency range of 10–100 kHz, and can be operated over a wide range of shock conditions during the complete high‐temperature pulse.

ISSN:0034-6748    

DOI:10.1063/1.1135948

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An apparatus for carrying out kinetic studies on the dry stress corrosion of threadlike metal specimens in well‐determined conditions of uniaxial stress is described. The results obtained by electrical conductivity measurements can easily be related to those obtained by thermogravimetry.

ISSN:0034-6748    

DOI:10.1063/1.1135949

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We describe a general purpose optically coupled dc isolation amplifier with voltage gain of 100, 20‐V peak‐to‐peak output swing, and response from dc to well over 250 kHz. Components used are all standard, commercially available items.

ISSN:0034-6748    

DOI:10.1063/1.1135950

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A simple method was devised for observing electron micrographs as well as diffraction figures from a given object. A dielectric emulsion composed of paraffin and barium titanate acted here as an electrostatic lens when charged up with the incident electrons. Electron diffraction figures could immediately be observed from the same object as for microscopy when the lens was mechanically removed out of the electron path.

ISSN:0034-6748    

DOI:10.1063/1.1135951

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A semiautomatic Hartshorn bridge has been designed to improve the complicated adjusting procedures of the bridge in the measurements of magnetic susceptibilities. The bridge is useful for a continuous recording of the susceptibility of a sample, especially when it varies with time.

ISSN:0034-6748    

DOI:10.1063/1.1135952

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A method for forming a thin metal foil seal capable of withstanding temperatures up to 500 °C and pressures up to 150 psig has been developed. The seal is formed by seam welding with an inexpensive electric marker.

ISSN:0034-6748    

DOI:10.1063/1.1135953

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A failure analysis technique for reconnecting aluminum metallization on planar IC devices is described. The technique, utilizing a conductive paint deposited on the device surface, is nondestructive and easily removable.

ISSN:0034-6748    

DOI:10.1063/1.1135954

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Sodium silicate may be used to make reliable transducer bonds for ultrasonics experiments near room temperature.

ISSN:0034-6748    

DOI:10.1063/1.1135931

出版商:AIP    

年代:1979

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1135932

出版商:AIP    

年代:1979

数据来源: AIP