Study of Raised Bridgewires in a Pyrotechnic Device.

摘要

Recent tests with actuators containing TiH sub 0 . sub 65 -KC10sub 4and conventional bridgewires have shown potential problems. Experiments have been conducted with raised bridgewires to try to demonstrate that they will give more reliable ignition. The test units were heated to 185exp 0 F for five hours,then cooled to -85exp 0 F for three hours,and the cycle repeated an additional six times. Following the thermal shock test,the units were exposed to a mechanical shock of 1500 g (200mu s pulse-approximate haversine) at ambient temperature. The acceleration was in a direction such that the powder column was forced away from the bridgewire. Each unit received a nondestructive Electrothermal Response Test (ETR) after fabrication and after each of the two environmental tests. The ETR tests showed that the thermal contact between the bridgewire and the powder was not degraded after exposure to the two environments. Each unit was ignited by an electrical pulse while being maintained at a low temperature. Each unit ignited and gave a satisfactory output. It was concluded that a thin layer of powder around the bridgewire is sufficient to render any wall effect negligible and that the principle of the raised bridgewire in contact with TiH sub 0 . sub 65 -KC10sub 4is worthy of further study,especially for use with ceramic headers which have a significantly higher thermal conductivity than glass headers. (ERA citation 02:060824)