Tests have begun in a small vacuum chamber. We’re getting the expected 5 sparks/second from our Emco high voltage supplies, building to around 5000 volts before the spark. This is the fallback failure mode for the high voltage supply which is redundant and normally able to do the mission rated 10 sparks/second.
We’re still doing ablation tests on closed cell foams, trying to get the most plasma. Several new ideas have come up for getting the spark to better contact the foam. As such, we’ve started a new version of the 3D printed engine. The propulsion principles are the same but we think the plasma production system can be significantly improved.
With vacuum testing comes the need for data collection in the vacuum chamber. A lot of people do their collection outside the chamber, passing signals through interconnects in the chamber wall. Don Smith has come up with an interesting way to gather pulse data at 16MHz without taxing the engine’s microprocessor. It’s all small enough to fit not only within the chamber, but within the satellite. After we build and blow up the first couple we’ll open source the data collector on Upverter.