A Direct Velocity Measurement Apparatus to Determine the Specific Electronic Charge

Citation

Ogier, Walter Thomas (1953) A Direct Velocity Measurement Apparatus to Determine the Specific Electronic Charge. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/WMM8-DH40. https://resolver.caltech.edu/CaltechETD:etd-04282003-155015

Abstract

An apparatus for the precision measurement of the charge to mass ratio of the electron by a direct velocity method is described. This apparatus uses a resonant cavity as a velocity selector. A carefully collimated beam of electrons is deflected by the rapidly rotating magnetic field produced across the center of a right circular cylindrical cavity operated in two TH[subscript 110] modes excited in time and space quadrature. Measurement is made of the beam voltages for which the beam receives no net transverse velocity from the cavity field. These voltages correspond to transit times of integral number of cycles in the field. From the cavity length and frequency the electron velocities are calculated, and from these velocities and the corresponding voltages the charge to mass ratio is obtained. Preliminary results are presented indicating that the attainable accuracy with this instrument should be better than one part in ten thousand.

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