Method of Locating the Axis of a Magnetic Field for Electron-Beam Focusing

Abstract

A quick and accurate method of locating the axis of a magnetic field of rotational symmetry is proposed. It is shown that the deviation of the field axis in direction or in position from the axis of a reference frame (the instrument axis) is found from the angular distribution of the transverse field component. This is detected by rotating a Hall probe on the instrument axis. Formulas for locating the axis of a uniform magnetic field and that of a periodic one for electron-beam focusing are derived, and have been experimentally confirmed. The instrument for the measurement is easily constructed, and the procedures are so simple that results can be obtained in a short time. Moreover, this can be done with error of less than a few percent and with resolution of the order of 10−4 rad in direction in case of uniform fields and of 10−4 in position (ratio to the inner radius of a magnetic field device) in case of periodic fields.

A Method for Producing a High Quality Solenoidal Field

“…The field quality has been measured, using the technique of Nishihara and Terada [8]. The resolution of our magnetic (Hall effect)…”