Step 8: Assemble the Vacuum System

To connect the vacuum pump to your cathode ray tube, you will need your brass pump to hose converter, about 2 feet of 1/4" rubber tubing, a pair of screw clamps, and some Teflon tape.

First, apply a few layers of Teflon tape over the middle of the steel brake line and over the middle of the threads on screw connector of your vacuum pump.

Second, install the pump to hose converter such that the Teflon tape is inside the interlocking threads of the screw connector and converter. Basically, this means you need to keep screwing the converter onto the pump until little or no Teflon tape is visible.

Third, apply a layer or two of Teflon tape over the hose end of the pump to hose converter and slide the hose over it until it is all the way on. Then, use a screw clamp to secure the hose.

Fourth, use a screw clamp to secure the other end of the hose over the Teflon tape on the steel brake line sticking out of the cathode ray tube.


The mechanical portion of the exercise is now complete.

/* If you're never worked with Teflon tape before, you should be warned that it's not actually tape; there's nothing sticky about it. The way you secure it is by wrapping it tightly around your work piece and then letting the vacuum pump do the rest. When you turn the pump on, the difference in pressure will cause it to assume whatever form you've forced it into and it will block air from leaking into the system (which is something that it's very good at). The first time I assembled my system, I decided not to put any tape over the vacuum pump's screw connector and I only used the screw clamp to hold the rubber tube in place. Big mistake! I wasn't able to reach anywhere near cathode ray tube operation pressure until I added that tape.

It is possible to assemble the system without a pump to hose converter if your pump's inlet is small enough for the rubber tube to fit over it. Instead of screwing on a converter, just force the hose over the Teflon tape and clamp it down: */
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>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>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>p.s enlarge the accel pic to see what im talking about</p>
<p> <br> <br>Its a great <br> pleasure reading your post.Its full of information I am looking for and I <br> love to post a comment that &quot;The content of your post is awesome&quot; <br> Great work.</p><p><a href="http://www.monacopropertylistings.com" rel="nofollow">appartamenti in vendita a Monaco</a></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>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>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?
Can I use copper for the anode?
That is intriguing - thanks, Xellers!
How could I do this project using different variables?
Could you use fluorescent highlighters for different color ray tubes instead of the phosphors from a fluorescent tube?
does this not produce large amounts of x-rays?
Nope - they don't have enough energy to penetrate the chamber with the acceleration voltage I'm using. Your concern is addressed in the safety step.
oh yeh, thats stupid of me. so is prolonged exposure to soft x-rays dangerous? and is using a fridge pump for vacuum and 30kv+ dangerous?
Prolonged exposure to any type of x-ray radiation is dangerous, but this produces very little and should not be operated for long periods of time. You won't be able to get 30kV of acceleration potential with only a fridge pump.
I wasn't able to detect any x-rays whatsoever coming off of my tube. I guess I was using a little lower voltage (a 6kv NST). Either way there is either no or negligible amounts of radiation coming off of this. I even tried reversing the polarity so the metal vacuum port was being bombarded with electrons (this is basically how ex-ray tubes work) and still no radiation was detected. For good measure I measured background for 5 min. and then turned the tube on and measured another 5 min. for each test. In no cases was the latter measurement higher than the former by a statistically significant amount (in fact a couple times it was lower).
ok, thanks for replying, so does that mean i wont be able to do this experiment with a fridge pump?
You can certainly try, but I doubt it - you can definitely make a simple gas discharge tube, but I don't think it will full enough vacuum for good cathode rays.
what pressure is the running at? because i have seen videos of people getting fridge pumps to works at 20millibar (10 torr)

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Bio: My name is Daniel Kramnik - I like building Tesla coils, quadrotors, and robots!
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