ISSN:0034-6748    

DOI:10.1063/1.1752342

出版商:AIP    

年代:1938

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752347

出版商:AIP    

年代:1938

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752348

出版商:AIP    

年代:1938

数据来源: AIP

摘要:

By the use of two type 37 vacuum tubes it has been found possible to design a high impedance voltmeter which possesses an approximate voltage squared characteristic, and is therefore suitable for the measurement of r.m.s. values of alternating potentials. The circuit of the voltmeter is such as to make the readings independent of appreciable fluctuations of the battery potential supplied to the tubes.

ISSN:0034-6748    

DOI:10.1063/1.1752338

出版商:AIP    

年代:1938

数据来源: AIP

摘要:

The construction of a magnetic electron microscope for the observation of self‐emitted and secondary electrons from the same surface is described. Primary and secondary images obtained are illustrated.

ISSN:0034-6748    

DOI:10.1063/1.1752339

出版商:AIP    

年代:1938

数据来源: AIP

摘要:

The automatic recording and computing comparator previously described has been adapted to the production of uniform and nonuniform scales. A photographic plate is clamped to the covered comparator carriage, where it is exposed to diminished images of a slit illuminated by an argon lamp which is made to flash periodically under control of the wave‐length dial of the comparator. A new automatic comparator with 22‐inch travel has been constructed, and the periodic errors of its screw have been reduced to less than 1 micron in amplitude by means of a new type of compensator operated by a three‐dimensional rotating cam. Scales up to 20 inches long have been produced photographically in ten minutes with this instrument, those with lines 0.01 mm wide and 2 mm long spaced at 0.1 mm intervals being found convenient for screw calibration. With such a scale the recording attachment will determine the correction curve for a screw in a few minutes. The correction cam can readily be shaped to offset the error found, and fairly cheap screws can thus be made to serve for precise measurements. A satisfactory method of mounting comparator screws on ball bearings has been devised, and this feature, together with the use of a half‐nut and ball‐bearing rollers under the comparator carriage, reduces to one‐third the torque required to operate the comparator, thus increasing its life, ease of operation, and precision.

ISSN:0034-6748    

DOI:10.1063/1.1752340

出版商:AIP    

年代:1938

数据来源: AIP

摘要:

A large cyclotron is described with particular reference to magnet design, ``ion‐source'' characteristics, radiofrequency requirements, optimum shape of the magnetic field, and the distribution in range of the high energy alpha‐particle beam. Increasing the ``ion‐source'' electron current above 400 ma was found to lower the efficiency of production of high speed ions. Investigation of the radiofrequency power losses showed that the anodes of the oscillators absorbed 35 percent of the total power, while the tank coil across the ``dees'' and the ``dees'' themselves took, respectively, 30 percent and 21 percent. The optimum arrangement of iron shims used for magnetic field correction was such that the average field at the middle of the pole was decidedly higher than at the edge.

ISSN:0034-6748    

DOI:10.1063/1.1752341

出版商:AIP    

年代:1938

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752343

出版商:AIP    

年代:1938

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752344

出版商:AIP    

年代:1938

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1752345

出版商:AIP    

年代:1938

数据来源: AIP