ISSN:0034-6748    

DOI:10.1063/1.1752281

出版商:AIP    

年代:1937

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752282

出版商:AIP    

年代:1937

数据来源: AIP

摘要:

A recording microphotometer, which gives an inked record, has been constructed. It utilizes a photoelectric cell as the light sensitive device. The recording is done with a Leeds and Northrup Speedomax recorder.

ISSN:0034-6748    

DOI:10.1063/1.1752283

出版商:AIP    

年代:1937

数据来源: AIP

摘要:

A description is given of an apparatus for measuring the total normal thermal emissivity of sheet materials up to ⅜ inches in thickness at temperatures from 140 to 500°F without contact or damage to the surfaces viewed. An analysis of possible errors is made which shows the outer limits of absolute values to be within ±1 percent of black‐body emission. A table of emissivities as measured are given with values from the literature included for comparison. By minimizing errors due to reflection, the values for poor emitters are found to be somewhat lower than usually reported and are held to be more accurate.

ISSN:0034-6748    

DOI:10.1063/1.1752284

出版商:AIP    

年代:1937

数据来源: AIP

摘要:

A tube is described for the utilization of the D — D reaction in the production of neutrons. A capillary arc ion source and a target of heavy ice are employed. The activation in Ag by the neutrons produced with 280 microamperes of unresolved ions at 200 kv was ten times that obtained when a 200 millicurie radon beryllium source was substituted.

ISSN:0034-6748    

DOI:10.1063/1.1752285

出版商:AIP    

年代:1937

数据来源: AIP

摘要:

The problem of the amplification of minute photoelectric currents by means of standard radio apparatus is discussed and a common reason for failure to obtain high sensitivity with ordinary tubes is pointed out. A radio receiving tube is described and its input resistance is raised from 108to 1013ohms by means of special use of its grids together with greatly reduced operating voltages. It is shown that this value of input resistance is higher than necessary for ordinary measurements made with the various electrometer type tubes. A comparison curve, showing the region of applicability for three tube types, is included.

ISSN:0034-6748    

DOI:10.1063/1.1752286

出版商:AIP    

年代:1937

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752287

出版商:AIP    

年代:1937

数据来源: AIP

摘要:

A new parallel wire method has been devised for measuring the dielectric constants of fluids and solids at ultra‐high frequencies. A relatively small sample in the form of a thin slab is required. The mathematical relation upon which the experimental determination depends involves only the wave‐length at which the measurements are made, the thickness of the sample, and a bridge shift along the parallel wires measured in air. This relation is derived, the experimental technique is outlined, and sample results obtained with water and alcohol are given.

ISSN:0034-6748    

DOI:10.1063/1.1752288

出版商:AIP    

年代:1937

数据来源: AIP

摘要:

A method is described whereby &bgr;‐magnesia windows may be sealed into heavy steel tubes, thus making them suitable for vacuum furnaces. These seals, utilizing copper or aluminum bands around the edges of the windows, have been made and tested up to 587°C without leaking. A needle valve is designed which permits the opening or closing of an evacuation port in the side of a vacuum furnace at will. This valve operates at the temperature of the furnace and does not introduce a cold spot into the absorption chamber. It has been tested up to 587°C and holds well against pressure differences of one atmosphere. Being made of stainless steel, it is relatively inert and is free from oxidation scale.

ISSN:0034-6748    

DOI:10.1063/1.1752289

出版商:AIP    

年代:1937

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752290

出版商:AIP    

年代:1937

数据来源: AIP