MDDC - 1079 
 
 UNITED STATES ATOMIC ENERGY COMMISSION 
 
 A 40-CENTIMETER TROCHOIDAL-TYPE MASS SPECTROMETER: TROCHOTRON 
 
 by 
 
 G. W. Monk 
 J. D. Graves 
 J. L. Horton 
 
 
 >>,> 
 
 Tennessee Eastman Corporation 
 
 This document consists of 1 page. 
 Date of Manuscript: April 2, 1947 
 Date Declassified: July 14, 1947 
 
 This document is issued for official use. 
 
 Its issuance does not constitute authority 
 
 to declassify copies or versions of the 
 
 same or similar content and title 
 
 and by the same author (s) 
 
 Technical Information Division, Oalt Ridge Directed Operations 
 Oak Ridge, Tennessee 
 
 £posTF5p7 
 
A 40-CENTIMETER TROCHOIDAL-TYPE MASS SPECTROMETER: TROCHOTRON 
 By G. W. Monk, J. D. Graves, and J. L. Horton 
 
 A large mass spectrometer in which the ion paths are prolate trochoids has been built, fol- 
 lowing the design principle of Bleakney and Hippie,* and has been in operation for several months. 
 This "trochotron" uses the theoretically perfect double-focussing properties of crossed uniform 
 electric an^ magnetic fields. The distance between the source and receiver slits in the grounded 
 plate is 40 cm, while in most other particulars the construction is similar to the prolate instru- 
 ment described by Bleakney and Hippie. An all-metal vacuum system is employed. An internal 
 voltage divider is used for the aluminum "picture frames" that establish the electrostatic field. 
 
 Operation with collector currents as high as 0.3 microampere has been entirely satisfactory 
 for masses up to Ce 140, which was the heaviest element studied extensively. The resolution is 
 approximately one-half the value expected from geometrical consideration using slits 0.020 inch 
 wide and 3 inches long. 
 
 Modifications of the apparatus are to be used in separation of stable isotopes in pure micro- 
 gram quantities and isotopic analysis. 
 
 The original instrument was designed and constructed under the direction of W. A. Arnold, 
 J. D. Trimmer, and H. W. Savage. 
 
 * Bleakney and Hippie, Phys. Rev. 53, 521 (1938). 
 
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