1. |
The Production of High Rotational Speed |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 429-435
L. E. MacHattie,
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摘要:
Small steel rotors have been suspended by an axial magnetic suspension using inductance control to effect vertical stabilization. They have been spun in vacuum by means of a rotating magnetic field having a frequency of the order of 100 kilocycles. Rod rotors tended to precess in the absence of horizontal damping. This was remedied by placing a copper block just above the upper end of the rod. A tapered length of drill rod ⅞″ long (max. diam.316′′) reached 36,000 r.p.s. before bending double due to the effect of centrifugal force. Steel balls have the advantage of no precession; however, on starting to spin they soon built up a circular orbital motion of increasing amplitude. A damping needle situated outside the vacuum system and immersed in oil was found to eliminate this motion satisfactorily. A332′′diam. ball has been spun to 110,000 r.p.s. This corresponds to a centripetal acceleration at the periphery of 58×106gravity. The rate of free deceleration at 106,000 r.p.s. was about 1 percent per hour. Rotational speed was measured by observing the rotor in stroboscopic light whose frequency could be matched with the speed of the rotor.
ISSN:0034-6748
DOI:10.1063/1.1769916
出版商:AIP
年代:1941
数据来源: AIP
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2. |
The Construction of a Mass Spectrometer for Isotope Analysis |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 435-441
Harrison Brown,
J. J. Mitchell,
Robert Dudley Fowler,
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摘要:
The complete constructional details for a 180° Dempster type mass spectrometer are given. The ions have a radius of curvature of 15 cm, and are accelerated through a potential of 2000 volts. Circuit diagrams for the voltage stabilizers and magnet current stabilizer are included.
ISSN:0034-6748
DOI:10.1063/1.1769917
出版商:AIP
年代:1941
数据来源: AIP
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3. |
Automatic Frequency Control for a Cyclotron |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 442-444
Robert B. Jacques,
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PDF (182KB)
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摘要:
This paper describes a discriminator circuit which automatically compensates for the changes due to thermal effects in the capacitive and inductive reactances of a quarter‐wave‐length dee line of a cyclotron. The unit thereby contributes to smoother power input.
ISSN:0034-6748
DOI:10.1063/1.1769918
出版商:AIP
年代:1941
数据来源: AIP
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4. |
A Pentode Lock‐In Amplifier of High Frequency Selectivity |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 444-447
Walter C. Michels,
Norma L. Curtis,
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PDF (251KB)
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摘要:
An amplifier which is based on the scheme of heterodyning the signal to be measured with a locking‐in voltage of the same frequency, as proposed originally by Cosens, is described and its characteristics are discussed. The particular design used, with the locking‐in voltage applied to the screen grids of two pentodes, possesses a distinct advantage over earlier instruments because the tubes operate on a linear portion of their transfer characteristics, reducing harmonic response, and also because the main power supply is direct current, so that there is little drain on the control supply. It is found that the response band can be given a width of the order of one cycle per second without undue inconvenience or expense.
ISSN:0034-6748
DOI:10.1063/1.1769919
出版商:AIP
年代:1941
数据来源: AIP
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5. |
Shielded Filament for an X‐Ray Tube |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 448-449
S. T. Stephenson,
W. L. Sylvester,
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ISSN:0034-6748
DOI:10.1063/1.1769921
出版商:AIP
年代:1941
数据来源: AIP
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6. |
A Three‐Phase Electrocardiograph Mixing Circuit |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 449-450
W. H. Jordan,
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PDF (132KB)
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ISSN:0034-6748
DOI:10.1063/1.1769922
出版商:AIP
年代:1941
数据来源: AIP
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7. |
New Instruments |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 450-452
Wm. F. Roeser,
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ISSN:0034-6748
DOI:10.1063/1.1769924
出版商:AIP
年代:1941
数据来源: AIP
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8. |
New Materials |
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Review of Scientific Instruments,
Volume 12,
Issue 9,
1941,
Page 453-457
A. R. Olpin,
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PDF (443KB)
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ISSN:0034-6748
DOI:10.1063/1.1769925
出版商:AIP
年代:1941
数据来源: AIP
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