Short Pulse Transient Radiation Effects on a 92 K-Bit Magnetic Bubble Memory System

Short-pulse transient radiation experiments were performed on a commercial (Texas Instruments TIB-0203) 92 K-bit magnetic bubble memory system. To test the bubble memory in actual operation, it was convenient to employ a TM 990/100 M-3 MNOS microcomputer system. Because of the low failure threshold that was experienced by this microcomputer (γF = 5×106 rads(Si)/sec), it was shielded during most of the test series. The BCA 0200A controller board was similarly shielded because of associated volatility of the data stored in the memory system at radiation levels above 3×107 rads(Si)/sec. With only the BKA 0203A bubble board exposed, the stored data survived 108 rads(Si)sec during read and write cycling. Radiation exposures above this level often produced errors during data cycling, but since facility-produced EMP and noise increased as the irradiation levels went up, precise failure mechanisms could not be isolated. During power-down, stored data survived 4×1010 rads(Si)/sec, the highest level that could be obtained from the facility in the test configuration employed. The conclusion that may be drawn from the tests is that when shielded or hardened electronics is used with the 92 K-bit magnetic bubble chip, data will be protected up to levels exceeding 108 rads (Si)/sec during normal operations. For levels exceeding the upset thresholds of the support electronics, redundant unbiased magnetic bubble memory may be employed as spares in applications where multiple exposures of transient radiation are not probable.