Plasma-Powered Thrusters For Your Homebrew Satellite Needs

It seems as though every week we see something that clearly shows we’re living in the future. The components we routinely incorporate into our projects would have seemed like science fiction only a few short years ago, but now we buy them online and have them shipped to us for pennies. And what can say we’ve arrived in the future more than off-the-shelf plasma thrusters for the DIY microsatellite market?

Although [Michael Bretti] does tell us that he plans to sell these thrusters eventually, they’re not quite ready for the market yet. The AIS-gPPT3-1C series that’s currently under testing is designed for the micro-est of satellites, the PocketQube, a format with a unit size only 5 cm on a side – an eighth the size of a 1U CubeSat. The thrusters are solid-fueled, with blocks of Teflon, PEEK, or Ultem that are ablated by a stream of plasma. The gaseous exhaust is accelerated and shaped by a magnetic nozzle that’s integrated right into the thruster. The thruster is mounted directly to a PCB containing the high-voltage supplies and control electronics to interface with the PocketQube’s systems. The 34-gram thrusters have enough fuel for perhaps 500 firings, although that and the specifics of performance are yet to be tested.

If you have any interest at all in space engineering or propulsion systems, [Michael]’s site is worth a look. There’s a wealth of data there, and reading it will give you a great appreciation for plasma physics. We’ve been down that road a lot lately, with cold plasma, thin-film plasma deposition, and even explaining the mystery of plasmatic grapes.

Thanks to [miguekf] for the tip.

Fail Of The Week: Toilets And High Voltage Do Not Mix

Imagine if you will that you are enthroned upon the porcelain, minding your own business while doing your business. You’re catching up on Hackaday on your phone – c’mon, admit it – when a whir and a buzz comes from behind you. You sit up in alarm, whereupon your lower back suddenly feels as if someone is scrubbing it with a steel wool pad. Then the real pain sets in as super-hot plasma lances into your skin, the smell of burning flesh fills the bathroom, and you crack your head on the towel bar trying to escape this torture chamber in a panic.

Sound good? Then [Vije Miller]’s plasma-powered toilet air freshener is a must-build for you. We’re not entirely sure where this was going, but the name of the project seems to indicate a desire to, ahem, clear the air near your derrière with the power of ions. While that might work – we’ve recently seen an electrostatic precipitator for 3D-printer fumes – the implementation here is a bit sketchy. The ball of steel wool? It was possibly intended as a way to disperse the ions, but it served as nothing more than fuel when touched by the plasma. The Contact-esque gimballed rings? Not a clue what they’re for, but they look cool. And hats off to [Vije] for the intricate 3D-printed parts, the geartrain and linkages, and the DIY slip rings.

It may be a head-scratcher of a build, but the video below is entertaining. Check out some of [Vije]’s other projects of dubious value, like his licorice launcher or the smartphone back scratcher.

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Vacuum Sputtering With A Homemade Magnetron

“You can never be too rich or too thin,” the saying goes, and when it comes to coatings, it’s true that thinner is often better. The way to truly thin coatings, ones that are sometimes only a few atoms thick, is physical vapor deposition, or PVD, a technique where a substance is transformed into a vapor and condensed onto a substrate, sometimes using a magnetron to create a plasma.

It sounds complicated, but with a few reasonable tools and a healthy respect for high voltages, a DIY magnetron for plasma sputtering can get you started. To be fair, [Justin Atkin] worked on his setup for years, hampered initially by having to settle for found parts and general scrap for his builds. As with many things, access to a lathe and the skills to use it proved to be enabling, allowing him to make custom parts like the feedthrough for the vacuum chamber as well as a liquid-cooled base, which prevents heat from ruining the magnets that concentrate the plasma onto the target metal. Using a high-voltage DC supply made from old microwave parts, [Justin] has been able to sputter copper films onto glass slides, with limited success using other metals. He also accidentally created a couple of dichroic mirrors by sputtering with copper oxides rather than pure copper. The video below has some beautiful shots of the ghostly green and purple glow.

A rig such as this opens up a lot of possibilities, from optics to DIY semiconductors. It may not be quite as elaborate as some PVD setups we’ve seen, but we’re still pretty impressed.

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Cold Plasma Torch Produces A Cleansing Flame That Never Consumes

It’s basically a lightsaber. Except smaller. And with an invisible blade. And cold to the touch. But other than that, this homebrew cold plasma torch (YouTube, embedded below) is just like the Jedi’s choice in elegant weaponry.

Perhaps we shouldn’t kid [Justin] given how hard he worked on this project – seventeen prototypes before hitting on the version seen in the video below – but he himself notes the underwhelming appearance of the torch without the benefit of long-exposure photography. That doesn’t detract from how cool this build is, pun intended. As [Justin] explains, cold plasma or non-equilibrium plasma is an ionized stream of gas where the electron temperature is much hotter than the temperature of the heavier, more thermally conductive species in the stream. It’s pretty common stuff, seen commercially in everything from mercury vapor lamps to microbial sterilization.

It’s the latter use that piqued [Justin]’s interest and resulted in a solid year of prototyping before dialing in a design using a flyback transformer to delivery the high voltage to a stream of argon flowing inside a capillary tube. The quartz tube acts as a dielectric that keeps electrons from escaping and allows argon to be ionized and wafted gently from the tube before it can reach thermal equilibrium. The result is a faint blue glowing flame that’s barely above room temperature but still has all the reactive properties of a plasma. The video shows all the details of construction and shows the torch in action.

Hats off to [Justin] for sticking with a difficult build and coming through it with an interesting and useful device. We’ve no doubt he’ll put it to good use in his DIY biohacking lab in the coming months.

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Grape Plasma Explained

You’ve probably seen the videos of a grape — cut almost totally in half — in a microwave creates a plasma. A recent physics paper studies the phenomenon with a lot of high-tech gear and now the actual mechanism is known. [Veritasium] interviews the scientists and explains the grape plasma phenomenon in plain language. You can see the video below or read the paper directly.

Turns out the grape is about 1/10 of the microwave frequency and the refractive index of the grape at microwave frequencies might be as much as ten. A whole grape can get all the microwaves trapped inside, but two grapes — or two halves — that touch create fields strong enough to ionize the air.

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DIY Arc Light Makes An Unnecessarily Powerful Bicycle Headlight

Remember when tricking out a bike with a headlight meant clamping a big, chrome, bullet-shaped light to your handlebar and bolting a small generator to your front fork? Turning on the headlight meant flipping the generator into contact with the front wheel, powering the incandescent bulb for the few feet it took for the drag thus introduced to grind you to a halt. This ridiculous arc-lamp bicycle headlight is not that. Not by a long shot.

We’re used to seeing [Alex] doing all manner of improbable, and sometimes impossible, things on his popular KREOSAN YouTube channel. And we’re also used to watching his videos in Russian, which detracts not a whit  from the entertainment value for Andglophones; subtitles are provided for the unadventurous, however. The electrodes for his arc light are graphite brushes from an electric streetcar, while the battery is an incredibly sketchy-looking collection of 98 18650 lithium-ion cells. A scary rat’s nest of coiled cable acts as a ballast to mitigate the effects of shorting when the arc is struck. The reflector is an old satellite TV dish covered in foil tape with the electrodes sitting in a makeshift holder where the feedhorn used to be. It’s bright, it’s noisy, it’s dangerous, and it smokes like a fiend, but we love it.

Mounting it to the front of the bike was just for fun, of course, and it works despite the janky nature of the construction. The neighbors into whose apartments the light was projected could not be reached for comment, but we assume they were as amused as we were.

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Add Some Edge To Your Blades With Blown-Arc Plasma

If you polled science fiction fans on what piece of technology portrayed by the movies that they most desire, chances are pretty good that the lightsabers from the Star Wars franchise would be near the top of the list. There’s just something about having that much power in the palm of your hand and still needing to be up close and personal to fight with it. Plus being able to melt holes in bulkheads is pretty keen, as are the cool sounds.

Sadly, the day we can shape and contain plasma in a blade-shaped field is probably pretty far off, but that didn’t stop [Alan Pan] from trying the next best thing: a handheld plasma-projecting blade. He starts with a basic Jacob’s ladder. We’ve seen many of these before, but the basic idea is to ionize the air between two parallel, vertical conductors; the hot plasma heats the air causing it to rise until it reaches the top and snuffs itself out, starting the process over again at the bottom. His twist is to force the plasma into a sheet between the electrodes with air from a leaf blower, forming a blown-arc plasma. That’s pretty cool looking by itself, but he also stretched the electrodes along razor-sharp wood planer blades, for extra danger. We have to admit that the thing looks pretty intimidating, even if the plasma doesn’t really pack bulkhead-melting thermal power. Check out the results in the video below.

We’d love to see [Alan] make good on his promise to make the whole thing self-contained with an electric ducted fan or mini jet engine. Even as it is, it’s still pretty neat. It’s not really his first lightsaber rodeo, but at least this one doesn’t need butane.

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