ISSN:0034-6748    

DOI:10.1063/1.1748660

出版商:AIP    

年代:1930

数据来源: AIP

摘要:

A brief review is given of the use of photographic plates for the recording of electrons. Photographic plates are rendered more sensitive to the action of electrons by the application of a small amount of certain oils; but whether oiled or not, photographic plates are insensitive to the action of electrons when they strike the plate with a speed of less than 25 equivalent volts. This work indicates that the sensitizing action of oil is largely due to cathodo‐luminescence of the oil, and that the failure of the photographic plate to record low speed electrons is due to the high electrical resistance of the photographic emulsion.Announcement is made of the discovery of the fact that metal surfaces are affected by electron bombardment in such a way that the bombarded regions react differently toward certain vapors than do the unbombarded regions. This effect has been observed even when the speed of the impinging electrons was only 12 equivalent volts. Experiments on silver and gold are presented in detail, and the practical use of the effect for electron recording demonstrated. Possible causes of the effect are also discussed.When the two methods for recording electrons are compared, it is found that the photographic method has the advantage of speed and ease of reproduction; while the metal method has the advantage of reliability, freedom from charging up, and insensitivity to light. Moreover, the metal method can be used for lower speed electrons than can the photographic method.

ISSN:0034-6748    

DOI:10.1063/1.1748661

出版商:AIP    

年代:1930

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1748662

出版商:AIP    

年代:1930

数据来源: AIP

摘要:

The spectrograph has four unique features which make it fitted for precise measurements (1) A slit system, consisting of five slits each one thousandth of an inch wide, excludes optical light and gives excellent collimation of the x‐rays. (2) A universal grating support permits the plane grating to be set at any desired angle and to be removed in vacuo from the path of the x‐rays without disturbing any adjustments. (3). A set of two parallel plate‐holders at a fixed and known distance apart, placed at right angles to the slit system, permits accurate measurements of angles from the lines recorded on the two plates. (4) An x‐ray tube with interchangeable targets is mounted on a micrometer slide permitting the focal spot to be readily lined up with the fixed slit system. The slit system, grating support and ways for the plate‐holders are mounted as one unit which may be completely removed from the rest of the spectrograph for the purpose of adjustment. The apparatus is mounted on heavy concrete blocks to avoid mechanical vibrations. The spectrograph is maintained at constant temperature. Typical spectra are shown.

ISSN:0034-6748    

DOI:10.1063/1.1748663

出版商:AIP    

年代:1930

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1748664

出版商:AIP    

年代:1930

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1748665

出版商:AIP    

年代:1930

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1748666

出版商:AIP    

年代:1930

数据来源: AIP

摘要:

A spherical bulb containing mercury vapor at 25°C and air at various pressures was excited to luminosity when placed in a fixed helical coil carrying damped high frequency currents developing a predominant electrostatic field. Range of frequency of excitation 1800 to 555 k., of pressure 3 to 60 microns, of current 0.8 to 1.6 amperes. Visual intensity measured by a flicker photometer.No simple relations were found to exist between visual intensity of the electrodeless discharge and air pressure, current or frequency, but consistent irregularities were observed.The visual intensity was a maximum at a pressure of about 3 microns for all values of the exciting current but the minimum measurable intensity shifted from higher to lower pressures as the exciting current was decreased. Periodic breaks were found to exist in curves showing visual intensity as a function of exciting current. Constant current and pressure maximum values of visual intensity were found for wave lengths of 252, 358, and 490 meters, corresponding to frequencies ofn, n+k,andn+2k.

ISSN:0034-6748    

DOI:10.1063/1.1748667

出版商:AIP    

年代:1930

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1748668

出版商:AIP    

年代:1930

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1748669

出版商:AIP    

年代:1930

数据来源: AIP