Electron Tree Bridal Gifts

[Mark] just sent us in this fascinating example of Lichtenberg Figures, or more commonly known as Captured Lightning.

He just got married yesterday to his beautiful wife [Charlie] and they wanted to do something different for their bridal party. They chose to capture lightning inside acrylic spheres. Quite an impressive gift if we do say so ourselves!

The funny thing is, I was just reading [Theo Gray’s] Mad Science book which explains this phenomena. These Lichtenberg Figures are created by blasting a beam of high energy electrons at a piece of acrylic. Many of the electrons get trapped inside the acrylic and form a plane of charge. When the acrylic object gets struck with a grounding  stud, a discharge path is formed and all the electrons escape, leaving a completely unique lightning-like path in their tracks.

Unfortunately to make these you’re going to need a linear accelerator; a very expensive machine that [Mark] was lucky enough to use through his work. However the couple didn’t stop there, they also designed the lighted base using a PIC12F1501 micro-controller to finish off the gifts!

See how they were made after the break! Just a heads up, the video is very loud when the electrons are fired! If you’re wearing headphones keep the volume low.

[Thanks Mark!]

34 thoughts on “Electron Tree Bridal Gifts

  1. Heads up for headphone users. For some reason they decided to have no sound at all until the giant machine turns on and obliterates your eardrums. So, turn down the volume instead of turning it up like I did…

    1. Nope, the energy of electrons from a CRT is orders of magnitude less then the LinAc can do on a daily basis…(there’s a good reason they cost more then a house)
      Not saying it’s DIY-impossible, but the only way is a linear accelerator…

      Also, note random crap in the image once the linac fires – that is the butload of braking radiation being produced, a normal house or garage are very far from suitable for this kind experiment ;-)

    2. I wondered that myself, and did a little Googling. While I’m far from an expert, I quickly got the impression that the beam from a CRT, or even a scanning electron microscope cranked to the max, is still woefully inadequate. I actually have access to an SEM, which is why I checked – but not a linac.

    3. Not well. To get this to work well, you need the electrons to penetrate a reasonable distance into the acrylic before coming to a stop. CRTs have an acceleration potential of around 15kV. Linacs like this have around 2.5MV. You can build one yourself for a few thousand if you are really resourceful. However, like one of the other commenters said, radiation is a major concern. You’d have to build a small building around the linac or operate it from a great distance. I’ve wanted to build one for a while now, but I don’t have the time or space.

    1. I’ll get in touch with Mark and I’m sure he’ll love to field your question! He did tell me the machine is not supposed to be used like this, so I suspect it’s not suppose to do that.

        1. Audio didn’t work on that video for me, not sure why. Was it a “sizzling sound reminiscent of frying eggs”?

          I read that quote in a paper on the Therac-25, detailing the story of hardware and software issues that led to it sometimes running at beyond normal power, leading to some fatalities. For geeks, and perhaps real-life medical mystery lovers, it was an interesting read:


          1. Thanks for recurring nightmares. Honestly if I ever in my life have to undergo radiation treatment, I’m gonna be overly involved and make damn sure they have calibrated the machine, double checked the programming, and verified everything. Even in recent times the amount of incorrect dosage caused by incorrect programming or unnoticed hardware failures is frightening.

          2. Therac-25 is a classic in the pitfalls of real time software. Things have gotten quite a bit better since then. (For reference – Therac was running on a PDP-11, with software written in assembler modified from the previous generation machine) The sounds people heard were most likely ionic discharges – smaller versions of what happened in the acrylic balls.

          3. Therac-25 esque issues are ancient history. It was pretty much a great example of how not to build a safe machine. Any dosage discrepancies or hardware failures on modern machines cause instant interlocks rendering the machine unusable until fixed.
            A lot of interlocks have to be purposely removed/wired out by someone in the know in order to create these electron trees.

    2. I’d wager that the noise and the hot pixels are a consequence of massive amounts of interference generated when the machine is running. We’re talking linear accelerator here. The internet tells me that you should expect some serious energy:

      “Medical Linear Accelerators:
      – Accelerate electrons in pulses to kinetic energies from 4 to 25 MeV.
      – Use non Use non-conservative microwave RF fields in the frequency range from 10.3 MHz (L band) to 10 band) to 10.4 MHz (X band), with the vast majority running at 2856
      MHz (S band).
      – Some provide beams only in S band Linear Accelerators the low megavolt range (4-6 MV), while others provide both photons and electrons at various energies. A typical
      modern high-energy linac can provide 2-3 photon energies.”

      As found here: http://www.aapm.org/meetings/09SS/documents/11Palta-PhotonBeamDosimetry.pdf

      That’s some serious juice.

      For comparison, the kinetic energy of a ‘standard’ CRT is on the order of 20 KeV.

      Interesting project, but I’d actually like to have more information about the medial equipment that was used.

  2. Hey guys! Sorry about the volume on the vids but I had to mute certain sections due to the conversations going on during recording and I didn’t want to publish anyone’s voice without permission. To answer the question regarding the noise; the machine does make this noise during treatments however there are usually a lot more covers on the machine so it’s not quite as loud; the noise is actually a byproduct of thyratron switching and klystron operation however were it not present an artificial noise would have to be added due to radiation regulations. The hot pixels and cintillations are also a normal byproduct.
    I don’t think you’d ever be able to do this with a CRT electron gun as the electrons here are energised up to the level of around 6 Megavolts, but if anyone wants to experiment I’d be interested in the outcome.
    Obviously I’m on my honeymoon at the moment so may not be able to get back to you guys as quickly as usual but feel free to ask more questions on here or on the post on http://entirelyopinionated.com.

  3. Beautiful!

    The only thing that could possibly make it cooler is a motorized base to slowly turn the sphere. A bit ambitious for gifts, I know, but I’d have to make that addition to my own.

    Here’s hoping for the day when we can all pick up a linac at the dollar store, right next to the Mr. Fusion.

  4. I can’t imaging handling the undischarged sphere with simple rubber gloves. It seems like the voltage necessary to drive out through over an inch of solid acrylic would not be stopped by a thin glove.

    1. Actually you can pretty safely handle them with bare hands, even when they are still discharging, it’s an insulator remember and the charge will only go via the dent created by the grounding stud.
      You do occasionally get a shock akin to static if you touch them before discharge.

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