When you think of a particle accelerator, you’re probably thinking of tens of kilometers of tube buried underground, at high vacuum, that uses precisely timed electromagnetic fields to push charged particles like electrons up to amazing speeds (and energies). However, it’s also possible to accelerate electrons in other ways, and lasers are a good bet. Although a laser-based particle accelerator can push electrons very effectively for a few centimeters, they top out at a relatively low maximum “speed” of a couple billion electron-volts, as opposed to the trillions of eV that you can get out of a really big traditional accelerator.
If only you could repeat the laser trick again, “hitting” the already-moving electrons from behind with another beam, you could boost them up to even higher energies. Doing so would take something like a one-way mirror that lets the electrons pass through, but that you could then bounce a laser beam off of. In a fantastic mixture of science and mother-of-invention-style hacking, these scientists from Lawrence Berkeley National Labs use plain-old VHS tape to make plasma mirrors to do just that. Why VHS tape? Because it’s cheap, flexible, and easy to move through the apparatus at high speeds.
The device works like this: a first laser beam passes through a jet of ionized gas and pulls some electrons with it. These electrons are then focused into a beam and pass through some (moving) VHS tape. The electrons punch a hole through the tape. In their wake they leave a hot plasma of mid-90s TV shows you never got around to watching. The second laser beam is then bounced off this plasma mirror and further accelerates the electron beam from behind. In principle, you could repeat this second stage enough times to build up the energy you needed, but for now the crew is working to characterize their single-stage beam. Getting the timing right on the second-stage beam is, naturally, non-trivial.
Anyone who has spent some time in a science lab knows that there are millions of these tiny get-it-done-quick hacks behind the scenes, but it’s nice to see one take center stage as well. If you’ve got stories of great lab hacks that you’d like to see us cover, post up in the comments!
Thanks [Bruce] for the tip, via Science Daily.
In the high-voltage world, a Jacob’s ladder is truly a sight to behold. They are often associated with mad scientist labs, due to both the awesome visual display and the sound that they make. A Jacob’s ladder is typically very simple. You need a high voltage electricity source and two bare wires. The wires are placed next to each other, almost in parallel. They form a slight “V” shape and are placed vertically. The system acts essentially as a short-circuit. The voltage is high enough to break through the air at the point where the wires are nearest to each other. The air rises as it heats up, moving the current path along with it. The result is the arc slowly raising upwards, extending in length. The sound also lowers in frequency as the arc gets longer, and once [Gristc] tuned his system just right the sound reminds us of the Holy Trilogy.
We’ve seen these made in the past with other types of transformers that typically put out around 15,000 Volts at 30mA. In this case, [Gristc] supersized the design using a much beefier transformer that puts out 11,000 Volts at 300mA. He runs the output from the transformer through eight microwave oven capacitors as a ballast. He says that without this, the system will immediately trip the circuit breakers in his house.
In the demo video below, you can see just how large the arc is. It appears to get about 10 inches long before breaking with a sound different from any Jacob’s ladders we’ve seen in the past as well. Continue reading “11,000 Volt Jacob’s Ladder Sounds Like a Lightsaber”
Experimentation with the unusual nature of things in the world is awesome… especially when the result is smokey glowing plasma. For this relatively simple project, [Peter Zotov] uses the purchase of his new vacuum pump as an excuse to build a mini vacuum chamber and demonstrate the effect his mosfet-based Gouriet-Clapp capacitive three-point oscillator has on it.
In this case, the illumination is caused due to the high-frequency electromagnetic field produced by the Gouriet-Clapp oscillator. [Peter] outlines a build for one of these, consisting of two different wound coils made from coated wire, some capacitors, a mosfet, potentiometer, and heat sink. When the oscillator is placed next to a gas discharge tube, it causes the space to emit light proportionate to the pressure conditions inside.
For his air tight and nearly air free enclosure, [Peter] uses a small glass jar with a latex glove as the fitting between it and a custom cut acrylic flange. With everything sandwiched snugly together, the vacuum hose inserted through the center of the flange should do its job in removing the air to less than 100 Pa. At this point, when the jar is placed next to the oscillator, it will work its physical magic…
[Peter] has his list of materials and schematics used for this project on his blog if you’re interested in taking a look at them yourself. Admittedly, it’d be helpful to hear a physicist chime in to explain with a bit more clarity how this trick is taking place and whether or not there are any risks involved. In any case, it’s quite the interesting experiment.
[Ben Krasnow] hacked together a method of cleaning sides using plasma. His setup uses a mechanical vacuum pump to evacuate a bell jar. This bell jar is wrapped with a copper coil, which is connected to an RF transmitter. By transmitting RF into the coil, plasma is created inside the bell jar.
Plasma cleaning is used extensively in the semiconductor industry. Depending on the gas used, it can have different cleaning effects. For example, an oxygen rich environment is very effective at breaking down organic bonds and removing hydrocarbons. It is used after manual cleaning to ensure that all impurities in the solvents used for cleaning are fully removed. According to [Ben], it’s possible to get a surface atomically clean using this process, and even remove the substrate if the energy levels are too high.
These machines are usually expensive and specialized, but [Ben] managed to cook one up on his bench. After the break, check out a video walk through of [Ben]’s plasma cleaner
Continue reading “Cleaning Slides with Plasma”
[Patrick] didn’t just want his name in lights. He wanted his name in glowing plasma explosions, made by sending thousands of volts through a very thin wire.
This project is an experiment in capturing high speed images of exploding wires. [Patrick] wanted to know if he could shape wires in such a way that they would explode into letters of plasma. Of course, photographic proof of this would be needed, and would make for an awesome logo in any event.
To get pictures of wire turning into plasma, [Patrick] first needed to construct the necessary electronics. A simple spark gap was constructed on a large plastic cutting board – an excellent high voltage insulator. The huge capacitors are charged with a pair of high voltage transformers, and the entire assembly is triggered with an optocoupler and a very beefy SCR.
Even though [Patrick] designed the system for a low propagation delay, there was still the matter of capturing an exploding wire on film. The camera delay varied by about 120μs, but with a really great camera trigger, [Patrick] eventually got some impressive pictures.
After getting the electronics and photography portion of the build down, [Patrick] turned to making letters out of expanding plasma. Simply shaping the wire into a letter shape before vaporizing it had no effect, so he turned to 3D printed channels to contain the plasma. After a few attempts, this actually worked, allowing him to form the letters L, U, and X in an expanding ball of vaporized wire.
Here’s a new take on the QR clock concept that uses an LCD display. The concept comes from the work [ch00f] put into his two versions of a QR clock (both of which used LED arrays). The time of day is encoded using the Quick Response Code standard. This version generates a new code each second which encapsulates date, hour, minute, and second information. If you look at the image on the left you’ll notice the code is not centered. Take a look at the video after the break and you’ll see that’s because it’s bouncing around the LCD like a screensaver. Watch a little longer and you’ll see the psychedelic effects shown in the image on the right.
A PIC32 is driving the display. It’s connected to a DCF77 radio module which feeds the system atomic clock data. The color plasma effects are used to show when the device has locked onto the radio signal.
Continue reading “LCD-based QR clock”
[Dearmash] put together this RGB LED display using triangles for each pixel. It’s an interesting deviation from the traditional grid layout. There are two video demos after the break. The first is a plasma-style pattern generated in Processing. The second is a spinning color wheel which would be perfect if synchronized with your Photoshop color spinner.
So the physical build is done, and now [Dearmash] is looking for a purpose for the device (isn’t that always the way it happens?). He mentions that the triangular layout looks cool, but makes text display almost impossible. Does anyone have any ideas on how to make this work? Right off the bat we could see side-scrolling a font similar to the Metallica logo’s M and A. Bu there must be some way to group these pixels together into readable characters. If you always use an upward and downward pointed triangle on the same row as a pixel it makes a parallelogram which would be used to display italicization characters.
Continue reading “Triangle-grid LED display”