Quest Q2G2 Igniter No Fire Current

The pulse width for these tests was 5 seconds and the successes showed rather chaotic behavior:

sample current pulse from a success

It appears that after the igniter burned through something happened to cause it to conduct current again. It might have been something mechanical bringing the wires into contact again or the burning pyrogen supporting conduction. In any case it suggests that the firing circuit may require some sort of current limiting to protect it from short circuits. Or at least a sharply limited pulse width.

Quest Q2G2 All Fire test levels

Because of the data from the all fire tests I started with tighter bounds. The most notable feature of this test series is that the variance is pretty high. There were failures at higher currents and successes at low currents. The end result was a high standard deviation.

The final estimated mean was 235mA with a standard deviation of 44mA. The no fire current (99.9%) for a 5s pulse is 130mA.

The average firing current with a five second pulse isn't much different than the average for a 100ms pulse. This indicates that the thermal time constant of the igniter (the time required to reach thermal equilibrium, more or less) is near 100ms. Probably less but certainly not much more.

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