The Theory of the Modified Aston-Type Mass-Spectrometer

[摘要] The theory of an Aston-type mass-spectrometer using acylindrical condenser and bringing all ions of the samespecific mass to a point focus by variation of the magneticfield alone is developed. The theory of the motion of anion in an inverse first-power electrostatic field is studiedunder the particular set of conditions where all ionsregardless of their energy enter the condenser normal to itsleading edge and at the median position in the gap. Taylorseries expressions have been obtained which give the exitposition, the square of the exit velocity, and the tangentof the angle of deflection in the field. The existence,uniqueness, continuity, and uniform convergence of theseseries solutions are established. The equation of the familyof straight lines which the ions follow beyond the electrostaticfield and before the magnetic field are obtained. Theexistence, location, and width of a virtual source areestablished for this system under the above conditions ofcollimation. Expressions for the coordinates of the faces ofthe magnetic pole pieces are obtained for the case where theleading and trailing faces are mirror images of one another,in the line containing the centers of curvature of the pathsof the ions in the magnetic field. The maximum mass-resolutionis obtained for a magnetic deflection of about one radian whenthe electric deflection is one fourth of a radian. A studyis made of the corrections for various edge effects in themagnetic field. Tables are given of the numerical resultsof this investigation.

[发布机构] University:California Institute of Technology;Department:Physics, Mathematics and Astronomy

[关键词] Physics