摘要:

A pump was constructed in a casing 10 cm in diam in which electrons are orbited around a central anode consisting of a tungsten rod supporting a titanium cylinder. Electrons have mean free paths of several hundred centimeters, they ionize inert gas and they heat the titanium cylinder to give sublimation. Some values determined for pumping speeds when sublimation rate is sufficient are 900 liters/sec for hydrogen, 500 liters/sec for nitrogen, 300 liters/sec for air, and 7 liters/sec for argon. Sticking probabilities were measured for active gases and for inert gas ions as a function of the ratio of atoms of gas bound to atoms of titanium deposited. The pump is very stable in operation; it is simple and dependable.

ISSN:0034-6748    

DOI:10.1063/1.1719315

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A convenient method to determine stress in thin films deposited on single crystalline silicon wafers is described. The film is treated as an elastic membrane attached to the edges of a thin circular disk. Due to the stress forces of the film, the substrate deforms elastically and assumes a parabolic curvature. This parabolic deflection is determined by measuring the substrate profile on the surface with a light section microscope. Knowing the curvature and the elastic constants of the substrate wafer, one can calculate the stress forces exerted by the film. The experimental accuracy of the method is about ±10%.

ISSN:0034-6748    

DOI:10.1063/1.1719333

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A description of an apparatus for flash photolysis kinetic spectroscopy is given. This apparatus allows spectra of transient species to be observed in the vacuum ultraviolet down to the fluorite cutoff and allows photolysis radiation with wavelengths as low as 1650 Å to be utilized.

ISSN:0034-6748    

DOI:10.1063/1.1719310

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The construction of this apparatus follows an initial investigation which has been reported by Weibel. The generator delivers 10 periods of 30 MW at 1.5 Mc to a 10‐&OHgr; load. Alternatively it can give 40 MW at 2 Mc. The technical feasibility of producing hundreds of megawatts for a longer time, as required in some plasma‐physics experiments, is examined.

ISSN:0034-6748    

DOI:10.1063/1.1719312

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Measurements of the pulse‐height distribution from electron multipliers excited by single electrons are interpreted in terms of the Poisson statistics to give the secondary emission coefficient and detection efficiency. It is shown that silver‐magnesium dynodes are characterized by a distribution of local values of the secondary emission coefficient.

ISSN:0034-6748    

DOI:10.1063/1.1719313

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The photoelectric yield of aluminum type 5086‐H32 containing 94% Al and 4% Mg has been measured at wavelengths between 300 and 1300 Å. At 584 Å the yield increased by 50% when the angle of incidence was changed from 0 to 50°. At 1026 Å the yield remained nearly constant for such a rotation. In general the yield was a function of the wavelength, the angle of incidence, and the degree of polarization of the incident radiation. The photoelectric yields were found to be stable and reproducible.

ISSN:0034-6748    

DOI:10.1063/1.1719314

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

This paper describes an apparatus for cooling an iron foil containing a radioactive impurity to a temperature in the range of 0.012 to 0.026°K by thermal contact with an adiabatically demagnetized chromium potassium alum salt pill. The purpose of the demagnetization is to orient the nuclei of the radioactive impurity. A superconducting solenoid is used to produce the high magnetic field required to remove the entropy from the chrome alum. The apparatus uses two helium Dewars—a large one which contains the superconducting magnet and a small one which contains the salt pill, the 1°K helium bath, and the radioactive sample. The salt pill is formed by pressing a mixture of chrome alum and Octoil S around 5000 0.076‐mm‐diam copper wires. The salt is supported by a graphite cylinder and helium exchange gas is used to establish heat contact between the salt and the 1°K helium bath. In one form of the apparatus the chrome alum salt and the sample are surrounded by a copper can which is cooled to 0.1°K by contact with a manganese ammonium sulfate salt pill located in the fringe field of the superconducting magnet. With the chrome alum pill alone, the sample temperature is 0.019 to 0.026°K; with the guarded salt pill the sample temperature is 0.012 to 0.016°K.

ISSN:0034-6748    

DOI:10.1063/1.1719316

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

An apparatus is described that will allow simultaneous tensile deformation and internal friction measurements. Kilocycle‐frequency internal‐friction measurements may be made as a function of strain amplitude between 10−10and 10−4strain. Tensile strains as large as several percent are possible with only moderate loss of accuracy in the damping measurements. Vibrations at the higher strain amplitudes affect the yield and flow stresses of the sample.

ISSN:0034-6748    

DOI:10.1063/1.1719317

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A microdensitometer is described that has the form of an attachment fitting over the ocular tube of a standard microscope. It periodically scans a stationary object which can be viewed at the same time by the eye. The electrical output of the densitometer is displayed on an oscilloscope screen, with linear or logarithmic readout. Maximum resolution is 1 micron using a 20× N.A.0.5 microscope objective. Measurements can be made of photographic films and of electron beam spots on fluorescent screens without modifying the instrument.

ISSN:0034-6748    

DOI:10.1063/1.1719318

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A continuous vertical scanning photosensitive device is described which is capable of monitoring the radiation intensity of chemiluminescent reactions in cylindrical flow reactors. The output from the photomultiplier is fed to a conventional millivolt recorder to obtain a plot of intensity as a function of time. This enables calculations to be made of concentrations and rate constants of reaction for the species taking part in the chemiluminescent reaction, if the reactions occurring are well understood. The system increases the accuracy of measuring rates of reaction, greatly shortens the time required to carry out an experiment, and is inexpensive to construct.

ISSN:0034-6748    

DOI:10.1063/1.1719319

出版商:AIP    

年代:1965

数据来源: AIP