MEASUREMENTS OF BUBBLE DRIVE FIELDS IN A T‐BAR CONFIGURATION

Studies are reported of the fields surrounding the T‐bar pattern commonly used in magnetic bubble propagation devices. Large, appropriately scaled, T‐bar circuits were used to experimentally determine the normal field patterns in the vicinity of the T‐bar elements. These patterns were determined with external drive fields having various in‐plane orientations. From these data the approximate stable position of the bubble was determined for each external field orientation. The magnitudes of the perpendicular (driving) field gradients were estimated from the changing field patterns and bubble velocities were calculated. The discussion of these results includes comparisons with available data on bubble velocity along the propagation path. Bubble oscillations normal to the propagation direction are noted.