The two basic facts to be aware of.<p>Momentum is mass times velocity. Energy is m v^2 / 2. Both with adjustments in the relativistic realm, which this barely gets to.<p>The maximum thrust per atom lost is going to be at insanely high velocity. The maximum thrust per unit energy is going to be at low velocity. Which makes ion thrusters great for slow changes of velocity when powered by unlimited solar power. But terrible for launch with a finite energy budget.<p>Useless trivia. A traditional rocket becomes more efficient if you mix some mercury into the fuel. The loss of energy is made up for by the extra mass. The collateral damage from the mercury is an environmental disaster though.<p>For a lot more, including the source of that trivia, I highly recommend reading <a href="https://library.sciencemadness.org/library/books/ignition.pdf" rel="nofollow">https://library.sciencemadness.org/library/books/ignition.pd...</a>.
I love this video for a number of reasons besides just general coolness. Specifically, the problem of the excess voltage caused by the oxide "skin" - and its solution (whack some fat resistors in there) - demonstrates a few really curious and often difficult to explain elements of engineering really well:<p>1. The problems you end up having won't be the ones you expect to have.<p>2. It's easy to shy away from burning time on better diagnostics, but the amount of time you'll waste by not doing so is often greater.<p>3. Sometimes you need to step out of the room and talk it over with a colleague who's not working on the same project.<p>The fact that this same problem plagued every iteration and it wasn't until it was fixed that the project turned from "banging head against wall" to "how cool is that" just adds so much to the video.<p>I love this and I am so pleased he got it working.