Performance of bubble memories under harsh conditions simulating severe transient radiation

A 7.5-μm-period field-access Permalloy magnetic bubble memory (MBM) with a 2.0-μm bubble (MemTech 7114, 4-Mb capacity, 50-kHz drive field) has been characterized under conditions of drive and current stress similar to that which occurs during severe transient radiation. The silicon-based peripheral devices that interface directly with the MBM are upset by the radiation, creating transients in the MBM function and drive currents. These transients were reproduced by artificially injecting positive and negative currents of various amplitudes and widths. The replicate function was most sensitive to the amplitude and phase of the injected disturbance. The swap function exhibits somewhat more tolerance to the disturbance, and only the width of the injected voltage transient is significant for disturbances to the drive waveform. Experimental results are presented, and failure mechanisms are discussed