Vacuum Sputtering With A Homemade Magnetron

July 23, 2019 by Dan Maloney 8 Comments

“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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Hacking When It Counts: The Magnetron Goes To War

June 11, 2018 by Dan Maloney 36 Comments

In 1940, England was in a dangerous predicament. The Nazi war machine had been sweeping across Europe for almost two years, claiming countries in a crescent from Norway to France and cutting off the island from the Continent. The Battle of Britain was raging in the skies above the English Channel and southern coast of the country, while the Blitz ravaged London with a nightly rain of bombs and terror. The entire country was mobilized, prepared for Hitler’s inevitable invasion force to sweep across the Channel and claim another victim.

We’ve seen before that no idea that could possibly help turn the tide was considered too risky or too wild to take a chance on. Indeed, many of the ideas that sprang from the fertile and desperate minds of British inventors went on to influence the course of the war in ways they could never have been predicted. But there was one invention that not only influenced the war but has a solid claim on being its key invention, one without which the outcome of the war almost certainly would have been far worse, and one that would become a critical technology of the post-war era that would lead directly to innovations in communications, material science, and beyond. And the risks taken to develop this idea, the cavity magnetron, and field usable systems based on it are breathtaking in their scope and audacity. Here’s how the magnetron went to war.

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Are Microwave Guns For Real?

October 23, 2017 by Lewin Day 65 Comments

Almost exactly one year ago, [Kreosan] published a video detailing an EM “weapon” built out of three magnetrons, some batteries, and a taser. It all seemed a bit too good to be true, so [Allen] decided to try and replicate the results for himself.

[Kreosan]’s original video was impressive, showing everything from home stereos to a humble moped exploding when in the presence of their powerful device. However, many of those watching the video doubted the footage. Most criticism centered around the nature of the power supply to the magnetron falling short of the usual 700-1000W seen in a microwave oven.

Initial testing with a single magnetron. This setup could light the bulb at a distance of a few centimeters.

[Allen] starts by experimenting with a single magnetron, successfully using it to light a compact fluorescent bulb at a range of a few centimeters. Scaling up to the full triple magnetron setup with a cardboard and foil feedhorn, [Allen] is, at best, able to crash a calculator at a distance of a few feet.

The microwaves cause no explosions, and the device doesn’t seem to have anywhere near the 50-foot range claimed by [Kreosan] for their device. [Allen] puts forth the theory that the explosions seen in the original footage are far more likely to be from small firecrackers rather than any electronic components dying from microwaves.

Overall it’s a solid attempt to recreate someone else’s work to verify the results, a cornerstone of science. We did bristle somewhat at the valiant 18650 being described as a “vape battery”, however. For more microwave goodness, check out this attempt to recreate the TSA’s body scanners .

Put Plasma To Work With This Basic Toolkit

April 21, 2017 by Dan Maloney 15 Comments

Fair warning: [Justin Atkin]’s video on how to make plasma, fusors, and magnetrons is a bit long. But it’s worth watching because he’s laying a foundation for a series of experiments with plasma, which looks like it will be a lot of fun.

After a nice primer on the physics of plasma, [Justin] goes into some detail about the basic tools of the trade: high voltage and high vacuum. A couple of scrap microwave oven transformers, a bridge rectifier, and a capacitor provide the 2000 volts DC output needed. It’s a workable setup, but we’ll take issue with the incredibly dangerous “scariac” autotransformer, popularized by [The King of Random]. It seems foolish to risk a painful death mixing water and line current when a 20-amp variac can be had for $100.

A decent vacuum pump will be needed too, of course; perhaps the money you can save by building your own Sprengel vacuum pump can be put toward the electrical budget. Vacuum chambers are cheap too — Mason jars with ground rims and holes drilled for accessories like spark plugs. Magnets mounted below one chamber formed a rudimentary magnetron, thankfully without the resonating cavities needed for producing microwaves. Another experiment attempted vapor deposition of titanium nitride.

It’s all pretty cool stuff, and we’re looking forward to more details and results. While we wait, feel free to check out the tons of plasma projects we’ve featured, from tiny plasma speakers to giant plasma tubes.

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Trio Of Magnetrons Power A Microwave Rifle

October 22, 2016 by Dan Maloney 107 Comments

Can you build a working EM weapon from three microwave ovens? Apparently, yes. Should you do so? Maybe not when the best safety gear you can muster is a metallized Mylar film fetish suit and a Hershey’s Kiss hat.

Proving that language need not be a barrier to perfect understanding of bad ideas, the video below tells you all you need to know, even without subtitles in the non-Russian language of your choice. [KREOSAN]’s build is obnoxiously obvious — three magnetrons mounted on a tin can “resonator” with a foil-covered waveguide at the business end. The magnetrons are tickled by a stun-gun that’s powered by a pack of 18650 batteries. The video shows some “experiments”, like lighting up unpowered CFL bulbs from about 15 meters away and releasing the Blue Smoke from the electrical system of a running motor scooter. Assuming they weren’t added in post, the artifacts in the video belie the gun’s lack of shielding for the operator. We doubt any of the ad hoc safety gear would provide any protection from the resulting microwaves, but we also doubt that it matters much when things have gotten this far.

We’re not too sure about this one — some of the zapping stunts look a little too conveniently explosive. It’s hard to tell the details without a translation, so maybe one of our Russian-speaking readers can pitch in on the comments. Although this isn’t [KRESOAN]’s first microwave rodeo, having melted a few lightbulbs with magnetrons before. Even seeing this we still consider EMP Weapons a figment of Hollywood’s imagination.

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Microwaving Things Outside Of The Microwave!

September 11, 2015 by James Hobson 48 Comments

DISCLAIMER: DO NOT TRY THIS AT HOME!

Ever wonder what would happen if you took a magnetron out of a microwave, strapped it to a stick, and pointed it at random everyday objects? Well, lucky for you a couple young Russians recorded their research before they presumably hurt themselves and were hospitalized, or maybe just became infertile — or caused cataracts — point is don’t do it.

They’ve taken a magnetron out of a microwave, and tied a soup can to the side of it to focus the microwaves. After discovering this, they did the next logical step — point it at various things and see what happens.

In this specific video (they have lots…) you can see them create plasma inside light bulbs, melt light bulbs, light up vacuum tubes, fluorescent bulbs, liquefy metal, and even catch a glimpse of radio waves.

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Ask Hackaday: The Many Uses Of Microwaves

March 9, 2015 by Will Sweatman 73 Comments

When most think of a microwave, they think of that little magic box that you can heat food in really fast. An entire industry of frozen foods has sprung up from the invention of the household microwave oven, and it would be difficult to find a household without one. You might be surprised that microwave ovens, or reactors to be more accurate, can also be found in chemistry labs and industrial complexes throughout the world. They are used in organic synthesis – many equipped with devices to monitor the pressure and temperature while heating. Most people probably don’t know that most food production facilities use microwave-based moisture solids analyzers. And there’s even an industry that uses microwaves with acids to dissolve or digest samples quickly. In this article, we’re going to look beyond the typical magnetron / HV power supply / electronics and instead focus on some other peculiarities of microwave reactors than you might not know.

Single vs Multimode

The typical microwave oven in the millions of households across the world is known as multimode type. In these, the microwaves will take on typical wavelike behavior like we learned about in physics 101. They will develop constructive and destructive interference patterns, causing ‘hot spots’ in the cavity. A reader tipped us off to this example, where [Lenore] uses a popular Indian snack food to observe radiation distribution in a multimode microwave cavity. Because of this, you need some type of turntable to move the food around the cavity to help even out the cooking. You can avoid the use of a turn table with what is known as a mode stirrer. This is basically a metal ‘fan’ that helps to spread the microwaves throughout the cavity. They can often be found in industrial microwaves. Next time you’re in the 7-11, take a look in the top of the cavity, and you will likely see one.

Multimode microwaves also require an isolator to protect the magnetron from reflected energy. These work like a diode, and do not let any microwaves bounce back and hit the magnetron. It absorbs the reflected energy and turns it into heat. It’s important to note that all microwave energy must be absorbed in a multimode cavity. What is not absorbed by the food will be absorbed by the isolator. Eventually, all isolators will fail from the heat stress. Think about that next time you’re nuking a small amount of food with a thousand watts!

Single Mode microwaves are what you will find in chemistry and research labs. In these, the cavity is tuned to the frequency of the magnetron – 2.45GHz. This allows for a uniform microwave field. There is no interference, and therefore no hot or cold spots. The microwave field is completely homogenous. Because of this, there is no reflected energy, and no need for an isolator. These traits allow single mode microwaves to be much smaller than multimode, and usually of a much lower power as there is a 100% transfer of energy into the sample. While most multimode microwaves are 1000+ watts, the typical single mode will be around 300 watts.

Power Measurement

Most microwave ovens only produce one power level. Power is measured and delivered by the amount of time the magnetron stays on. So if you were running something at 50% power for 1 minute, the magnetron would be on for a total of 30 seconds. You can measure the output power of any microwave by heating 1 liter of water at 100% power for 2 minutes. Multiply the difference in temperature by 35, and that is your power in watts.

There are other types of microwaves that control power by adjusting the current through the magnetron. This type of control is often utilized by moisture solids analyzers, where are more precise control is needed to keep samples from burning.

Have you used a microwave ~~and an arduino~~ for something other than cooking food? Let us know in the comments!

Thanks to [konnigito] for the tip!