Open-source R&D, engineering, and testing of plasma and ion thruster systems for nanosatellites at a hobbyist-level budget.

Joined March 2018
Sometimes wish I had a few U in volume to work with for Hall, that's practically a warehouse compared to PocketQube and 1U Cubesat volume restrictions! Still a work in progress, but it's getting closer every test! Think I'm hitting the fundamental limit for scaling at this point
#CNES CEO @PhBaptiste enjoying two great 🇫🇷 delights: pastries and the smallest Hall thruster in the world! 🛰️ @CNES
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Of course I couldn't resist the industry standard banana for scale. Don't have much funding, but hey, not bad for $300/month average funding developing ultra compact solid Adamantane fueled Hall thrusters!
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Pastries are indeed a delight, but I don't know about being the smallest in the world anymore! AIS is now pushing full Hall systems down to 1/8U sizes, attempting to bring Hall technology to PocketQube levels!
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Filament is at full power, sublimation heater is on, vacuum is still at 1.5x19^-5 Torr. Hopefully I have some fuel remaining. Now, I wait and monitor Faraday cup current.
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So since the system is already set up, I figured I'd give this another shot tonight. I don't know if I still have enough fuel, but let's see what happens. The AHT1-PQ Pico Hall Thruster is pumped down and ready to go for testing. Updates in the thread below!
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Filament neutralizer and sublimation heater are both currently on. Filament at 2.6W power, sublimator at slightly less than nominal this time at 4W. Chamber pressure now at 1x10^-5 Torr.
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Heater at nominal power at 5W, anode voltage increased to 600V, and filament power at around 7W. Vacuum still slightly increasing, no signs of ionization or beam yet.
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And we have confirmed beam, at nearly 40W filament power, about on par with the first EHT1 End Hall test!
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Holy crap, all of a sudden current just spiked up a ton! We definitely have ignition!!!
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Turning up filament power, we are now maxing out beam current on the galvanometer! So, it turns out that having a source of electrons *kind of* actually makes a massive, massive difference for ignition and operation of a Hall thruster.
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So I swapped in my current shunt monitor and am reading out directly now. At 10uA/V, I am currently reading an average of 185V on the Faraday cup, giving a beam current of 1.85mA! Holy shit, I'm going to need to do some additional calculations and see where that puts me!
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Playing around with filament power, it appears that I peak at 2.5mA of beam current at 1mTorr pressure given 50W of filament neutralizer power. However, further increasing the neutralizer power, beam starts to rapidly drop off.
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Just for reference, here is a quick video of me cycling the filament neutralizer power up to max of 50W then down again. Unfortunately the filament is so bright you can't see the plasma, but there are some hints and flashes of ionization and discharge here and there.
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The AHT1-PQ Pico Hall Thruster is loaded up and ready to go for testing tonight! This is the 8th ignition test, and the first time running with a tungsten filament neutralizer. System is already at full vacuum, so we are ready to start! Updates in the thread below!
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While I'm waiting on the final parts for the VAT1 to arrive, I rigged up the AHT1-PQ Pico Hall Thruster to run with a tungsten filament neutralizer. I have been trying to avoid this as long as possible, but I may have no choice now. Looking at attempting ignition tonight!
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As a look back, the very first ignition test I ran way back at the beginning of the year with the prior EHT1 End Hall build was successful in extracting beam using a filament, paving the way for later ignition with the first gen GDN1 hollow cathode.
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Also interesting to note the performance graphs, particularly thrust/ISP/mass flow, as well as mass utilization efficiency. This really exemplifies that at very low power (like where I am aiming at sub-30W class systems), performance optimization is really, really tough! (19/)
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Looking back through the paper, the answer is already here in the graphs! So the lower ISP can in fact be contributed to the overall quite low mass utilization efficiency. That checks out exactly with my estimated calculations.
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I did however receive the new modified Somos PerFORM lower housing from @Xometry, which will be swapped in immediately after the next test with the standard housing. In theory, this should possibly bring the lifetime to over 100k shots with only 1mm extra depth.
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Finally, I started experimenting with a new process for applying the graphite layer to the insulator. Hopefully with this new method and the actual low-current onboard supplies, I should at least not have anymore catastrophic thermal runaway from over-conduction of the graphite
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