摘要:

A magnetically confined, oscillating electron bombardment source has been designed which delivers high currents of noble gas ions in the 1‐ to 10‐keV energy range. The energy spread of the beam was 2±1 eV using an anode potential of 45 V. Pressure in the source chamber was measured during source operation so that accurate gas efficiency measurements could be made. The optimum gas efficiency obtained for argon at 5‐kV extraction potential and an operating pressure of 4×10−4Torr was 59%. Mass analysis of source output showed that when the source was operated with research grade argon (99.999% pure) impurity ions in the beam consisted of only 0.50% N2+, 0.75% O2+, 0.75% H2O+, and 0.70% Ar++. Filament life is extremely long, well over 750 h. Analysis of ion production rate and plasma density shows that a large contribution to electron emission is made by the secondary electrons produced at the tungsten filament due to positive ion bombardment. The secondary electron emission current was found to be as much as 30% of the true thermionic emission current and is not negligible as previous investigators have assumed.

ISSN:0034-6748    

DOI:10.1063/1.1718022

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A new method is described for detecting vacuum uv radiation. This radiation is converted to visible light in two steps, the first being creation of photoelectrons at a high voltage cathode, the second consisting of stopping these electrons in a scintillator at ground potential. The visible scintillations are detected with a standard photomultiplier. The system has been compared with a sodium salicylate detector, using a vacuum uv monochromator and a steady light source. Spectral lines between 500 and 1300 Å have readily been recorded. Compared to other systems, the new detector offers a number of advantages which are discussed. Preliminary results for pulsed light sources indicate that the method is also useful for studying phenomena whose time scales are of the order of 1 &mgr;sec.

ISSN:0034-6748    

DOI:10.1063/1.1718023

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An ignitron‐switched impulse generator has been developed, capable of providing a variable output voltage of from 0.6 to 90 kV with no circuit alterations. The generator consists of 6 capacitor stages, yielding a total energy of 5000 J at 90 kV, and is discharged with a single trigger pulse. The discharge time can be controlled to within 0.1 &mgr;sec.

ISSN:0034-6748    

DOI:10.1063/1.1718024

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Total neutron reflection from Cu, Fe, Cd, and glass mirrors was studied. The variation of the reflection coefficient vs glancing angle for a neutron wavelength of 1.161 Å was measured. The results obtained show that passing from a polished mirror to a ground mirror leads to a fourfold decrease of the reflection coefficient and a threefold increase of the half‐width of the rocking curve. The following values for the scattering lengths were obtained:fFe=(9.16±0.13)10−13cm;fCu=(7.46±0.15)10−13cm;fCd=(4.9±0.2)10−13cm. The penetration depth of totally reflected neutrons was measured and a value of 130 Å was found for a copper mirror.

ISSN:0034-6748    

DOI:10.1063/1.1718025

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A magnetic lens system designed from studies made with computing machines has been built and used at the Brookhaven cosmotron. It collected pions of 1020 MeV/c mean momentum produced at a target in the external proton beam, selected a narrow momentum bandwidth from a continuous momentum spectrum, recombined the selected momenta, and refocused the pions to an image of unit magnification. The effective solid angle of acceptance was 5.04×10−3sr and the momentum band pass width was ±30 MeV/c. The measured particle yield on 1 in.2at the focus was 5×105for 6×1010internal 3BeV/c protons; 27% were positive pions and 73% were protons.

ISSN:0034-6748    

DOI:10.1063/1.1718026

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A description is given of the materials, tools, and techniques used to make a successful gaseous optical maser whose output windows are oriented at the Brewster angle in respect to the beam axis.

ISSN:0034-6748    

DOI:10.1063/1.1718027

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An apparatus for the measurement of thermal conductivity in the range 1.7 to 300°K is described. Precautions on the use of gold‐cobalt thermocouples as well as details on automatic operation of the equipment are included. A qualitative analysis of the transient behavior indicates a method for detecting errors in the measured thermal conductivity values.

ISSN:0034-6748    

DOI:10.1063/1.1718028

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A high speed plane grating monochromatic illuminator intended for the vacuum ultraviolet and using nonparallel light is described. The light undergoes only two reflections between entrance slit and exit slit. Entrance slit and exit slit are on the principal axis of an ellipsoidal mirror, thereby eliminating astigmatism and spherical aberration.

ISSN:0034-6748    

DOI:10.1063/1.1718029

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A new tensile machine for thin specimens is described. Specially designed grips for both films and thin wires, and other features of the machine are described, and it is explained how the difficulties encountered in conventional machines are avoided. The actual testing procedure is given.

ISSN:0034-6748    

DOI:10.1063/1.1718030

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The generation of uniform magnetic fields over extended regions of space by means of circular coils of large cross‐sectional area is analyzed. It is shown by an extension of Garrett's theory of axially symmetric magnetic fields that the optimum shape of the coil cross section can be found analytically without numerical integration over the winding area. The theory is illustrated by application to Helmholtz coils and double Helmholtz coils of rectangular cross section. Choice of the optimum dimensions makes it possible to generate very uniform fields of great intensity.

ISSN:0034-6748    

DOI:10.1063/1.1718031

出版商:AIP    

年代:1962

数据来源: AIP