摘要:

A new instrument for surface pressure measurements using a floating‐foil technique has been constructed. The instrument makes use of a probe in the form of a thin foil suspended at the gas/liquid or liquid/liquid interface tension. The present instrument has a dynamic range of 0.1–70 mN/m and a sensitivity better than 0.1 mN/m. Its speed of response is 50 ms but much faster measurements are possible. Measurements on behenic acid and cholesterol films on water and on a cerebroside film at a heptane/water interface are presented.

ISSN:0034-6748    

DOI:10.1063/1.1135991

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A compound carbon thermometer consisting of an abreast connection of a carbon Speer resistor and a carbon Allen‐Bradley resistor was tested in the temperature interval 0.3–100 K, an interval which generally requires two independent resistors to be covered. The characteristics, sensitivity, and analytical handling of the resistance versus temperature data are discussed and compared with the corresponding behavior of other thermometers. The satisfactory performance of the compound carbon device contributes to the extension of wide‐range thermometry to 0.3 K.

ISSN:0034-6748    

DOI:10.1063/1.1135992

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A high‐pressure stopped‐flow apparatus was constructed which could be operative at hydrostatic pressures up to 3 kbar. Some preparative results on anionic &sgr;‐complex formation reactions are presented up to 1.5 kbar between 2,4,6‐trinitrobenzene (I) and hydroxide ion and between compound (I) and sulfite ion in water. It was found that this apparatus was sufficient to follow a chemical reaction whose half‐life was longer than several milliseconds.

ISSN:0034-6748    

DOI:10.1063/1.1135993

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A high‐average‐power short‐pulse gas discharge is described. This consists of a volume‐preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse‐charged from a high‐repetition‐rate Marx‐bank generator, and is switched by a high‐repetition‐rate segmented rail gap. The operation of this discharge under conditions typical of rare‐gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW.

ISSN:0034-6748    

DOI:10.1063/1.1135994

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

This paper describes an apparatus which allows the routine measurement of the magnetization of small ferrite samples using the well‐known extraction method. In contrast to the classical extraction method, however, this device makes use of a high‐permeability magnetic circuit that serves both to apply the bias field and to collect the sample flux. This design, together with a signal sampling technique, allows an unusually high sensitivity for this type of method (magnetic moment resolution is 5×10−5&mgr;em). The apparatus is described in detail and a brief theory of its function is given. Finally, the device usefulness is illustrated by some measurement results referring to Ga YIG spheres that are used in ferrimagnetic resonators.

ISSN:0034-6748    

DOI:10.1063/1.1135995

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We describe a high‐temperature reference load designed for calibration of microwave radiometers at frequencies of 80–150 GHz. An effective temperature of 410 K and a power reflection coefficient of less than 5×10−4have been measured at frequencies between 85 and 95 GHz.

ISSN:0034-6748    

DOI:10.1063/1.1135996

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A CO2‐laser interferometer with heterodyne detection has been built to measure electron line densities of plasmas in the range of 1018to 5×1022m−2. Heterodyne operation is accomplished by using two counteracting acousto‐optic modulators at a difference frequency of 500 kHz. A digital phase comparator is used to obtain direct read‐out of the phase shift. The time resolution is 3.5 &mgr;s.

ISSN:0034-6748    

DOI:10.1063/1.1135997

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An ultrahigh‐vacuum (UHV) differentially pumped low‐energy (50–3000 eV) ion beam system for theinsituirradiation of specimens in a UHV atom‐probe field‐ion microscope (FIM) was designed and constructed. The ion beam system consisted of a Finkelstein‐type ion source, an Einzel lens, and a magnetic mass analyzer. The ion source was connected to the analyzer chamber by small apertures which resulted in differential pumping between the ion source and the analyzer chamber; during a typicalinsituirradiation of a specimen in the atom‐probe FIM the total pressure was maintained at ≈10−7Torr. In the case of helium ion irradiation the optimum ion‐current density was ≈0.5 &mgr;A cm−2for 300‐eV He+ions at the atom‐probe FIM specimen. After the completion of a helium ion irradiation the pumpdown time from 5×10−7to ≈3×10−10Torr in the atom‐probe FIM chamber was 0.5 h.

ISSN:0034-6748    

DOI:10.1063/1.1135998

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A technique for measuring the magnetostriction coefficients of epitaxial garnet films on 50‐mm‐diam wafers is described. The measurement is based on the shift of the microwave ferrimagnetic resonance produced by stressing the film, which is achieved by supporting the wafer around its circumference and reducing the atmospheric pressure on one side. A simple, nonresonant transmission microwave spectrometer which is well suited for measurements on large wafers is also described.

ISSN:0034-6748    

DOI:10.1063/1.1135999

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

In the course of constructing an apparatus suitable for studies of nuclear magnetic resonance at high tempertures and high fields we developed a furnace with a new heating element which has been applied for the first time to NMR studies. The furnace can work in a 8‐T field of a superconducting magnet system at temperatures up to 2200 K. Because of its geometrical form the heating element does not cause any measurable disturbing magnetic fields resulting from the heating current, and has many advantages compared to conventional heating elements. The temperature at which, up to this moment, we could observe NMR in external fields of 8 T amounts to 1200 K. The specifically adapted NMR probe works at radio frequencies up to 50 MHz. With this apparatus we carried out measurements of the magnitude, sign, and temperature dependence of the Knight shift of Mo in molybdenum metal.

ISSN:0034-6748    

DOI:10.1063/1.1136000

出版商:AIP    

年代:1979

数据来源: AIP