Electron-Optical Investigation of the Origin of Asymmetries in Air-Cored Solenoids

The field asymmetries introduced in winding air-cored solenoids are investigated theoretically by treating the solenoid as a suitably deformed single turn. Regarding the solenoid as an electron lens, aberrations are calculated for the various field integrals. Using a novel method of measuring aberrations, these are compared with results obtained from carefully wound test lenses.