Learn how to build your own subatomic particle accelerator in a weekend! This simple project will allow you to investigate a variety of intriguing effects including magnetic deflection of an electron beam, Crookes dark space, plasma striations in a gas discharge tube, and many others. It can easily be used for a high school physics or science fair project and is compact enough to be demonstrated virtually anywhere.

You could be accelerating electrons to non-relativistic velocities after a trip to Home Depot and a visit to your local AC repair store and neon sign shop! Best of all, no advanced electrical or mechanical knowledge or tools are required.

Judges, see step 12 for contest entry details.

Here's some video evidence:

Thanks for all the support, guys! This project was featured on Hackaday, Slashgear, Engadget, Gizmodo, Gadgetblog, Tecmundo, Matuk, Zedomax DIY, and Make, as well as in the weekly newsletter and multiple times on our own front page!

Please don't forget to rate/vote!


Step 1: Design/Theory

As complex as the idea of a particle accelerator might seem, it's actually strikingly simple to implement. The design we will be using was first created in the late 19th century by J.J. Thomson and subsequently used to make several important discoveries about the fundamental nature of the atom and the electron. Later, in the early 20th century, Cockroft and Walton (yup, the same hooligans responsible for the voltage multiplier) used a similar design to build the first true electrostatic linear accelerator, or "static linac" for short. Nowadays, advanced versions of this type of accelerator are commonly used for radiotherapy and ion implantation.

Essentially, our cathode ray tube is just two electrodes in a vacuum chamber with a high voltage applied between them. When enough of the air in the chamber has been removed, electrons will freely accelerate from the negative electrode (cathode) towards the positive electrode (anode). However, instead of impacting the anode and returning to the power supply, some electrons will fly right past it and keep going until they hit a glass wall.

Some interesting effects that can be observed at this stage are sputtering and magnetic deflection.


If the acceleration potential is high enough, then some electrons striking the anode will have enough energy to knock metal ions right off the electrode. These ions will be deposited on the walls of the chamber near the anode and will create a silvery band somewhat reminiscent of the "getter" inside of an old vacuum tube.

Magnetic Deflection:

In physics, we all learned the Lorentz force law ( F = q[E + v x B] ), or the force on a point charge due to electromagnetic fields. In this context, it tells us that electrons will be accelerated from the cathode to the anode due E, the electrostatic field created by the high voltage power supply and that those electrons will also be accelerated by another field, B, in a manner that is dependent on the velocity, v, of those electrons. Since the velocity vectors of the electrons will be pointing roughly from the cathode to the the anode without an external magnetic field, we can use this to find out what effect a magnetic field will have if we introduce one.

Let's say we bring a magnet close to the tube while it's energized and we align it so that its field is roughly normal to the surface of the vacuum chamber. If we compute qv x B, we will find that the force due to the magnetic field is perpendicular to the paths of the electrons and to the magnetic field (by the definition of a cross product). In other words, the magnet curves the paths of the electrons and this effect is amplified by the duration that the electrons spend in the field. This effect can easily be observed inside of our cathode ray tube if a magnet is present nearby.

I've included a diagram of the mechanical construction of the accelerator to give a rough idea of how everything will work.
When one takes a doorknob to accelerate particles it's... glorious.
This is outstanding. One of the best at-home particle physics projects I've seen on I'bles (neither the <a href="http://thecyclotronkids.org/">cyclotron</a> nor the <a href="http://www.tidbit77.blogspot.com/">fusion reactor</a> have writeups :-).<br><br>Thanks especially for including the (non-relativistic) physics background!
<p>Actually the voltage multiplier was discovered in 1919, by <a href="https://en.wikipedia.org/wiki/Heinrich_Greinacher" rel="nofollow">Heinrich Greinacher</a>. It was only used and popularised by Cockroft and Walton.</p>
<p>How can I convert 120V to 1kV</p>
<p>Please don't. There is a much safer way: Buy an electric flyswatter, remove racket, BAM at least 1kv</p>
<p>a microwave oven transformer will convert 120V to 2KV, but be VERY CAREFUL with those, I suggest current limiting the crap out of them with a variac or capacitors or inductors in series with the primary. Seriously, those are some of the most dangerous transformers you can get your hands on, the small ones supply 500+watts at 2KV, so .25A (AKA enough to easily end your life if you aren't careful) is the lowest one will be able to supply, and most microwaves only use a half wave rectifier, so the actual power output can easily be double the rating of the microwave.</p><p>Just remember rule #1 for electricity: Don't be an idiot, and you will be fine. With proper precautions, such as current limiting and not making yourself part of the circuit, MOTs are perfectly safe to use.</p>
<p>So if I had mercury gas in there and bombarded it. I will lose protons and have gold atoms?</p>
No, you will have a mercury discharge tube.
<p>Thank you for this, I plan on using your schematics and implementing this into a project of mine. I went to university for this , and you did a better job explaining and executing an example than my instructors efforts. *clink</p>
<p>On your oscilloscope project if all you want to do is simple deflection of the electron beam over a relatively small phosphor screen, I suggest that you use an electrostatic deflection setup, they are easier to build and were the very first method used in the old phosphor cathode ray tubes used in this manner and in early radar</p>
<p>hey,could a particle target at the bottom of the machine so the electrons could hit the object at the bottom like a element or somthing ,this is what i mean,how to make plutonium,dont get bad ideas,first,you find urainum 238,then make it so it can fit in the eletron accelrators tin target,so eletrons hit it then after an hour you have pu-239 not the fission kind 238, the pic below is what i mean,thank u</p>
<p>Um, this device can bombard a sample at the bottom of the bottle with electrons. To transform a uranium sample into plutonium, you would need to bombard it with neutrons. Neutrons are a totally different subnuclear particle than an electron. The device needed to produce neutrons is a fission reactor, not an accelerator. </p><p>Plus, you've got it backwards. Pu-239 is the bomb kind of plutonium; Pu-238 is the kind that just gets hot and is used to power spacecraft out where sunlight is too weak to use solar panels. </p><p>You need to look up a book on Amazon called The Radioactive Boy Scout, and read the Wikipedia article on David Hahn. Be careful.</p>
<p>p.s enlarge the accel pic to see what im talking about</p>
<p>Cool and easy build!</p><p>I used one of those new plastic cork. I drilled a hole, used a barbed connector and a copious amount of epoxy.</p><p>Of note, the bottle was still containing a few drops of water and it refused to work until the vacuum pump had forced all the water to evaporate. </p><p>Over time, I've seen many hues of blue, red, orange...</p><p>The power comes from a simple flyback transformer driven by 12v and a 555 oscillator.</p>
<p>Nice, I would love to see a pic/schematics of your flyback converter.</p>
<p>can i use a vacuum instead of the vacuum pump</p>
<p>could you use a vacuum cleaner instead of the vacuum pump</p>
<p>I have tried this but couldn't get the beam and I'm trying to figure out the problem. I used a vacuum gauge and it reached 27 Hg inches of vacuum. Also I applied up to 10 kV. Any recommendations highly appreciated. Thanks.</p>
<p>I made it. Its Awesome!</p>
Is there any way you could seal off the vacuum and continue to run the tube w o the pump?
<p>I would like to think, &quot;yes!&quot; Try adding a valve in line with the tubing. While you're at it ad a gauge for fun. Let the device do its thing and close the valve then turn off the pump. Depending on the quality of your valve it may not last long, but hey! Another question to solve! Anyways that's what I intend to try. </p>
<p>Thanks so much for this. I had recently become obsessed with Cathode Ray Tubes and their essential place in history and being able to make one with your instructions made it all the better. I blogged about it like crazy here: </p><p><a href="http://www.partofthething.com/thoughts/?p=738" rel="nofollow">http://www.partofthething.com/thoughts/?p=738</a></p><p>I was running like 150 Watts through it and the anode epoxy kept melting and releasing the seal. I tried 5 minute epoxy, automotive goop, and finally settled on J.B. Weld, which can handle up to 600F. So far so good. <br></p><p><a href="http://www.partofthething.com/thoughts/?p=738" rel="nofollow">http://www.partofthething.com/thought</a></p>
<p>Wow!! Very insteristing!! <br>I liked!! =)</p>
<p>May I know how the electrons are ripped out of the doorknob to be accelerated? Also, is the light emitted due to the excitation of the electrons?</p><p>P.S I apologise for my lack of scientific knowledge.</p>
<p>Do i need a high vacuum? are 100 hpa enough? (or does it get lower when i fill it with steam and let it cool down?)</p>
<p>And are 1-4 kv enough?</p>
<p>All I wanted to do is make some X-Rays.</p>
<p>ok, this is not funny anymore. If my girlfriend finds I am building a subatomic particle accelerator in my room, I will need to move to a hotel.</p>
<p>Hi. I am attempting to do a project on voltage and electron speed for my 8th grade science project, and this instructable has been very helpful, but the only issue I've had with producing all of the materials for the project was when I attempted to find a relatively affordable power supply. Most have been running upwards of 600 dollars and that is simply not feasible. Do you have any suggestions? Thank you!</p>
You're probably looking at something that's a well-regulated switching supply for professional lab use. You can get away with a kill-a-watt, variac, and neon sign transformer + rectifier and filter, which shouldn't be more than $100 total with some careful eBaying.
<p>Thanks! I really do appriciate you taking the time to post this instructable, and replying to questions. My Sci-Fair sponser wanted me to do something daring. Looks like I've found it in this project.</p>
<p>Can someone please answer my question(it is the #4 down).</p>
<p>for my science fair apparently you need a hypothesis and experiment ;do you know any that I would be able to do.</p><p>P.S I all ready made the electron accelerator.</p>
<p>Hi, I just made this particle accelerator and I was confused on what I was seeing. I was using a copper anode and the test started just like you showed. I had a non-fixed 18 kv power supply and 60 cm of vacuum. There was a constant purple stream touching the anode with about an inch of crooke's effect. After about 45 seconds the stream turned white like it usually does when the bottle gets hot and the contaminent is killed. Then, all of the sudden there was a huge discharge. The stream came down in a tornado-like fation then went back up and there was just a swirling white tornado touching the side with 3 inches of crooke's effect. There were a few electric lighting- like strikes at the end of the anode before it repeated the process. I have a video below. Please let me know your thoughts.</p><p><iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/x2JNxAcbOl4" width="500"></iframe></p>
Very nice job!<br><br>Unfortunately, I don't have any background in plasma physics, so I can't say what's causing the effects you're seeing. It does appear that you are getting a better vacuum than I did, though.<br><br>One thing to be careful about here is the production of x-rays that can penetrate the glass vessel. With less than 10kV to 15kV of accelerating potential, the x-rays are stopped by the glass, but above that they can start making it through. Ideally, you would want to test for this with a Geiger counter, but if you don't have access to one, you can just lower the potential somewhat and stay back and operate everything remotely to keep your exposure as low as possible. I'd also keep a sheet of acrylic or other transparent plastic between you and the tube, as it is at risk of imploding.<br><br>If you have the materials to make another tube, try extracting some phosphors from the CRT screen (look up how to do this safely), then mix them with water, pour it into the tube, and let it dry out at the bottom. This way, you'll be able to see where the electron beam strikes the bottom of the tube (I suspect it will be everywhere, since the beam is not focused). Then, you can experiment with other electron gun designs and deflect the beam with a magnet.<br><br>Good luck, have fun, and stay safe!
Thanks for the feedback. I'm going to implement your suggestions.
<p>Its 5 pascals enough vacuum???</p>
<p>This is a very good instructable.</p><p>One question though. Any problems with implosion of the wine bottle while you were experimenting?</p>
<p>Could this be powered with a van de graaff generator? I'm new to doing these types of projects and am thinking this might be a safer option (thinking about amps).</p>
You should have got your vacuum pump from here:http://viot.us/HVAC/product_info.php?products_id=43. It was only about 160 dollars. Also, how much did the neon sign transformer cost you. I got my wine bottle for free.
<p>hi ninja .. your link give me error </p><p>so can you give another link</p>
i got one of the same rating for $15 plus $18 shipping, the trick is to find a used non-GFI unit on ebay that is still guarunteed working,and buy from a top rated seller.
(referring to the Neon Sign Transformer)
<p>Very cool :)</p><p>I ran across this crowdfunding platform a while back: <a href="https://experiment.com/" rel="nofollow"> https://experiment.com/</a></p><p>It might be useful? I think I saw some other more science oriented crowd funding sites elsewhere too.</p>
<p>May I please have a list of materials? I am aspiring particle physicist and would like to do this. </p><p>Thank you! </p>
I would just like to know how far you've gotten with your open-source accelerator.
You should try to focus the beam with an electromagnet :)
Would it be possible to attach the anode to the bottom of the bottle?

About This Instructable




Bio: My name is Daniel Kramnik - I like building Tesla coils, quadrotors, and robots!
More by Xellers:Build a Robotic Arm for the Science Olympiad DIY Electron Accelerator: A Cathode Ray Tube in a Wine Bottle How To Build A Spark Gap Tesla Coil (SGTC) 
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