#video #tutorial on #vacuum for electron tubes by #Signal-Ditch, explaining atmospheres, pascals, bar, torr, and millimeters of mercury, Pirani vacuum gauges, ion vacuum gauges, thermocouple convection vacuum gauges, and capacitance manometers. Mostly cartoon animations and screenshots. But he has a long series of hand-drawn diagrams about the design of his high-vacuum system, step by step.
#Breaking-Taps #video on doping silicon with lasers. With phosphoric acid. Explains how his IR fiber laser penetrates too deeply to be ideal and how hot-probe tests find positive (Seebeck?) voltage for N-type doping, as produced by phosphorus, and negative voltage for P-type doping. But he hasn’t been able to fabricate a PN junction on his P-type wafer yet. So apparently to avoid Schottky contacts you have to use “titanium and aluminum” (titanium-coated aluminum?) for the N-type probe and just plain aluminum for the P-type probe (or a highly-doped N-type region), both annealed at 480°.
#Advanced-Tinkering #video on turbomolecular problems. #vacuum #toread
#Alpha-Phoenix #video on #UHV #vacuum for molecular beam epitaxy (#MBE), explaining copper gaskets. Apparently MBEs are all equipped with quadrupole mass spectrometers to help in tracing UHV leaks, which give you a molecular mass spectrum calibrated in daltons, which is pretty cool since you can see spikes for individual isotopes, and you spray helium at your flanges. He also used a random bubble-wrap bag to raise the helium concentration around the suspected leak, and some masking tape to tape off a candidate joint. He mentions that there’s a kind of epoxy “leak seal” option when tightening the bolts isn’t good enough. An unfortunate amount of talking-head footage, but still informative.
#video on #optics at #ASML by Huygens Optics, discussing how getting more than one order of diffraction from your shadow mask into your imaging optics can improve the resolution of the resulting image. #precision #manufacturing
#video #toread #formina on visiting #Argentina and seeing the Subte
#Breaking-Taps #video on high-entropy alloys #toread
#NileRed #video about metal glass #materials, specifically Vitreloy 1, an alloy of zirconium (41.2 mol%), beryllium (“the asbestos of metals”, 22.5%), titanium (13.8%), copper (12.5%), and nickel (10%). Shows how to make a lab-scale arc melter from a common arc welding power supply! Tungsten electrode, water-cooled copper crucible, argon-filled glass chamber. But he ended up buying one on AliBaba instead; the final price was US$14440, including US$1570 of freight. Vitreloy 1 vitrifies when cooling even as slowly as 1°/s, so the water-cooled copper crucible was enough. Really astonishing viscous glassy goo behavior at 36'43", like sugar syrup instead of any metal I’ve ever seen. (It also shatters like glass when he cuts it with bolt cutters). He found suction casting of the Vitreloy to be very difficult, as on his first four attempts the metal didn’t fill the mold at all. On his fifth attempt, with 30% more metal, he successfully cast a metal disc, and similarly on attempts 6, 7, and 8. But then it wasn’t insanely bouncy like he expected, a problem he was able to fix with superglue. Video has a comment by “jaskaran_singh_saini” saying, “The metallic glasses I invented have been the most recent major advancement in this area. (...) The thing Nile mentioned about the metallic glass not being safe to grind and polish because of beryllium is not true. Once the beryllium has been absorbed into the metal matrix, it is very safe. I literally produced thousands of these metallic glasses in my lab during my PhD, and some in very big sizes and they are all safe.”
#video #toread about someone who fled the #USA for #Argentina #politics
Alan Kay’s #paper on the Early #History of #Smalltalk and #OO