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Build your own demo of a particle accelerator! Answered

This was originally posted by an I'bles user in the "Feedback" forum. I've suggested he repost his questions under Science, and hope to answer them there.

In the mean time, this video from the March 2008 issue of Symmetry Magazine (a joint SLAC/Fermilab publication) is really cute. The original article's video includes a bunch of related items which are worth checking out themselves.

The high voltage (at least 50kV, I think) DC supply needs to be pretty stable -- you can't just throw a rectifier bridge onto a wall cord, but other than that, the project would be extremely simple to build.

I've sent Dr. Johnson an e-mail to see if I can get more detailed specs.

Update 4 Jan 2009: Todd Johnson and I have exchanged a couple of e-mails about this project (d**n, I love the collegiality of the scientific world!).

For the DC power supply, he used a potted module (i.e., an enclosed unit with no accessible or dangerous components) designed for use in a negative ion generator (like the "Ionic Breeze"). He bought the unit surpus from http://www.goldmine-elec-products.com/prodinfo.asp?number=G9695 .

The bowl you see in the video was custom made from acrylic. I thought something like a Pyrex mixing bowl would work, but the "corner" where the flat base joins the spherical body introduces a barrier to the ball doing what it should do.

The coating on the ping-pong ball is something called http://www.goldmine-elec-products.com/prodinfo.asp?number=G16133
"wire glue"], touted as a substitute for solder. For this project, he covered the conductive paint with some clear Krylon for protection.

Dr. Johnson and I are discussing the possibility of collaborating on an Instructable for this project. As a result of the video publicity, he's already gotten some inquiries on how to build it, so this would be an appropriate venue. He has a substantial amount of performance data and physics background on the device, which we will include in the ultimate publication.



hey, i am planning on making this for a school assignment, but i was wondering what you'd recommend for the power supply!

I see that the link in the text is "sold out." You want a high voltage _potted_ DC supply (that is, a completely sealed unit with no exposed parts except for the wires). If you have access to a "plasma ball" or "negative ion generator" you could remove the supply from one of those. If you have a decent small electronics store in your local area, you should talk to the folks who work there; they are likely to have good recommendations.

hey, i am planning on making this for a school assignment, but i was wondering what you'd recommend for the power supply!

why it needs high voltage and not low voltage, is the speed dependent on how high the voltage is?

Yes, the speed is dependent on the voltage. Voltage is like gravity (steepness) or pressure: at low voltage, the charge doesn't get pushed very much, so doesn't move very fast.

@kelseymh...did Todd Johnson replied on what is the range of required voltage?

From Kelsey's original post:

"The high voltage (at least 50kV, I think) DC supply needs to be pretty stable . . . "

my e-mail is , victoria-nsecrets@hotmail.com

Hi, someone can send me an email saying how can i turn on this, i have to put the flyback somewhere or the lamp? I have to hurry up , my school project is for 27 of october

is 1000v enough to make it accelerate?

does the ping pong ball really accelerate? if it does it will slip away

I don't understand your question. The ball is accelerated parallel to the surface of the bowl, which is roughly perpendicular to gravity. Think of it like those "motorcycle in a cage" circus stunts.

I've updated the topic text with information from a couple of e-mail exchanges I've had with Todd Johnson at Fermilab.

The potted DC module that you speak of in the article above mentions it was designed for use in a negative ion generator. The link for it at Goldmine shows that that product is not listed/available anymore. Is there an alternative that can be found somehwere?

I did find this at Goldmine though and wonder if it would work (it's only list at 7.5kv). http://www.goldmine-elec-products.com/prodinfo.asp?number=G1783

I'm interested in building this for a physic class and would be ideal.

Thanks in advance.

I'm sorry; I don't know of a replacement part. You might contact Dr. Johnson at Fermilab directly (use the staff directory there) and see what suggestion he has.

Also, an Instructables user built one themselves using a flyback transformer for the power supply.

7.5 kV ought to be enough, but I can't prove it, and I'd hate for you to spend money on something that turned out not to work.

Building this for a physics class (or having the students do the build) would be really awesome! It is a great demonstration, and a few sparks just makes it all the better for the students, eh?


I don't know if you can view this


, but I used a salad bowl and some aluminum tape. The juice is from a flyback transformer harvested from a crt. The driver for the transformer is a 65w, (true 65 watts) compact flourescent lightbulb . I used the coating from electronic gold mine, like Kelseymh mentions above. If a few of you are interested, I'll make an ible.  I bought a mixing bowl at Walmart for $5.  It has a flat bottom, so I won't have to start it manually.

Congratulations! Yes, definitely create an Instructable for this. Make sure you credit Dr. Johnson's work, but other than that, it's all yours!

Unfortunately, only Facebook members can view that video :-(

I knew the facebook thing was inferior, but I wasn't allowed to post it here, because of it's size. I think. Kiteman offered to post it on youtube, so we'll put a link here when it's done.

No worries! Kiteman sent me a link to the video. It is quite impressive! The minor arcing is actually a nice way for the viewer to see that the device is active. I did find it hard to tell whether the ping-pong ball was actualy being maintained by the accelerator, or just coasting on inertia, but that's a minor issue. I really encourage you to do a full I'ble for this. Make sure you take lots of pictures as you go through each step of the fabrication, and talk about what you needed to do more or less carefully. This isn't a trivial project, and you deserve lots of credit at being so successful.

Accelerating or coasting?

I think accelerating - see how the ball suddenly slows when the power goes?

(I have a feeling that he tripped a breaker, since the lights went at the same moment.)

Those are excellent - if you made that first one longer, in a trough or gutter, you could present it as a cannon as well.

Right, I've been thinking about routing a grove in a 2x4 and taping it. What I really want is some HotWheels trac. If it goes that fast against all that tight centrifical force, I want to know how fast, how high it can climb with a long, straight runway, or of course a larger circle. Greater speed with a larger circle would be an excellent example of why we need larger and larger colliders.

I've just had this sudden image of a ten-foot loop of HotWheels track, with a ball thundering round...

Combined with a soundtrack of high-voltage snap and crackle...

I agree with the person in the background, even though some energy is lost in the sparking, the sparking makes it "cooler" :-)

Hey Goodhart. If you like sparks check this one out. https://www.facebook.com/MasterMcElhannon?ref=profile#!/video/video.php?v=1488239813308

WOOT! Congratulations, and I'm glad you got Featured for this. There are things you could add (in particular intelligent safety warnings), but it's really great as is.

Awww! I read the title to mean "How to build your own particle accelerator: a demo" Imagine my disppointment when I realize it means "How to build your own demo of a particle accelerator. :-D

I made the same mistake. Cool demo, though...

Yes, very cool, and possibly simple enough for either classroom demonstration, or even a student project. I've send Todd an e-mail to see if he has the power supply specs (I guess he used a surplus magnet supply, but I don't know). FNAL is shut down for the holidays, so I don't expect a reply before next week. If I get an answer, I'll update the topic. I'm not going to write an I'ble, as I don't really have the time (with the baby :-) to build it myself.

Update I got a reply from Todd Johnson today; I'll update the topic later (or tomorrow) with the power supply details. It turns out he's familiar with I'bles already, so I'm going to find out if (a) he's a member, and (b) if he'd be willing to contribute photos etc. to create an I'ble.

Hey Kelseymn, I built a temporary failure using a flyback for my hv. I'll try the negative ion generator next. It seems like the outer curve in the bowl would not affect the earlier motion of the ball, so I'm using a salad bowl. Any circular motion at all is all I want at the moment. Did you get any voltages from Todd, or is there an ible that i just can't find?

Well, he used a 15 kV supply, so you need to be pretty carefully with the attachments (potting, no sharp points, etc. I don't think there's an Instructable out there. Killerjackalope was going to try one, but I don't think that happened. Good luck!

I want to thank you for this thread and your reply. Ok, maybe I wasn't getting 15kv, and I see what you mean about sharp edges, (like the corona leaking from a vandegraff) I got a few twiches, and that's giving me the steam to try some more.

Thanks for you quick reply, Kelseymh. Well, the ion generator didn't do anything either. It's a 12v input, so it may have been too small. A flyback ought to produce that. I'm scared I'll burn up my volt meter if I test it. How exactly would I estimate hv? (size of the arc?) I made a conductive paint with graphite powder, and painted the ping pong ball. I used aluminum tape. Nothing was perfectly smooth. Even so, I didn't get the slightest hint of atraction/repulsion. I confess I didn't use a bowl with a flat bottom, and that caused the ball to create an arc upon leaving one ribbon to another, (near the center). But if that were the main problem, it should have shown some tendency to maintain its momentum when I started it off spinning further out. No such luck. I'll try a cake mixing bowl tomorrow, and cut my tape into thinner strips. I wonder how many ohms would be acceptable accross the surface of the ball.

Hmm, seems like the title is misleading enough to draw those of us that would love to build a simple particle accelerator ;-), which, if I am not mistaken, is actually kind of what goes on inside a TV picture tube with the electron gun, etc. at least to some minor extent, yes?

Nevertheless, it is still a cool demo.

Fine, fine, fine :-) Adrian, Kiteman, and Goodhart, I've edited the title to be a bit clearer. I can't change the URL, of course :-/

. Illegitimi nil carborundum.* <snicker>

*Faux Latin rulez heehee

Yes, the electron gun (which is what produces the cathode rays) is exactly a particle accelerator. Electrons are liberated from a hot filament, then accelerated electrostatically through a series of grids (wire mesh, basically) set at increasing voltages.

The identical system, on a larger scale, is how the electrons are produced for injection into the SLAC linear accelerator. A metal plate coated with cesium is heated up and illuminated with a laser. Electrons are ejected from the cesium via the photoelectric effect (thanks, Einstein!), and accelerated electrostatically up to a couple of MeV, for injection into the linac.

Cool! Thanks for completing my incomplete understanding on that......so, if 30 people throw away tv's and.......nah, that won't work LOL


9 years ago

are these common materials? i would love to make one!

Another I'bles member is working on a detailed construction I'ble for this. The materials are fairly common -- a plastic or glass bowl (but see some of the notes), adhesive copper tape, and the power supply mentioned above. Read the information above and the video if you want to try it yourself, or wait for the I'ble :-)

i have read the info but its not enough to make one unless its as simple as it looks. Ill check in for the intructable and if you find it be sure to notify me, please.