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I will be modifying it because....you need to be able to make it rain to buy a 4.5" CF cross. I'm looking at doing a similar layout but with an ISO 80 cross and manual valves (primarily cost...I think it'd be cool to have a control system to make modifications without getting x-ray exposure) and the. Probably working with just the single recommended 2-stage Amazon pump to get down to 5-ish microns.
I should say that I am not suggesting that you buy all of these parts directly from a manufacturer. I found all of these parts (except for the HV feedthrough) on eBay. Of course eBay parts are sometimes a gamble and it is important to make sure that the listing either says that the knife edges are undamaged, or has good pictures of the faces and knife edges.
Feel free to replicate any part of my setup that you think would be useful. I would also like to eventually change the manual valves to pneumatic or servo, but I want to focus on getting neutrons first. It is also mentioned previously, but the view port and the HV feedthrough have lead separating the chamber from the operator station. The X-rays are really not that bad until around 60kV, which I really won't be operating at.
The stand for the chamber is made from sections of 1515 T-slot aluminum extrusion. There is a lot of modular hardware out there for this stuff, making it easy to change the supports to fit your design. It is also easy to hand-saw through, so you don't need expensive tools. Here is an image of the stand:
Fusor chamber stand made from 1515 T-slot aluminum extrusion.
All of these sections are held together with 90 degree T-slot hardware found on Amazon. Definitely research the T-slot before buying any as there seems to be two different styles of slots that are not entirely compatible with each other (which I learned the hard way).
I'm heading towards making a poor man's version of this rig I particularly like the bench layout...very clean and designed for minimum components/hoses and direct fitting. Very nice concept.
I've been looking on ebay and I haven't had much luck yet. I'm certainly not paying $800 for a CF cross either lol I'm actually thinking of going ISO which isn't quite as nice but much cheaper. I am in touch with a Chinese vacuum parts manufacturer and their ISO-K stuff was suuuuppper cheap....so cheap that I asked them to quote their CF prices. I'm waiting to hear back but they may make it affordable. Generally I've had very good luck with Chinese ...well anything...turns out 90% of what we use daily comes from there anyway lol
I found the rolling bench setup really nice because I don't yet have a permanent place for it to go. I would just caution you that if you have a movable setup, make sure you have some checklist or system that prevents you from turning on the system until the whole thing is connected to the grounding that is needed. If you forget this step, the chamber and bench have potential to kill you, so be very sure of this. I found a connector that has some sense pins, so if the system is not plugged into the two grounds, I cannot power it up.
Deals on the CF components pop up once in a while on eBay, but I have not explored the Chinese manufacturers for CF parts so I cannot comment on their quality. While you are designing your system, just keep a lookout on eBay and see if you can snag anything good. I paid $280 for this 4.5" CF cross, and about $100 for the 2.75" cross. The 4.5" cross seems to have a bit of residue from whatever it was used in previously, but this hasn't had an effect on my system yet other than a spectacular green fluorescence above 30kV (it almost looks like fluorescent uranium minerals under blacklight).
I used cheaper Chinese parts specifically for the rough vacuum side with the KF parts as there are multiple sellers on eBay that ship new parts from China. I haven't had any issues with these parts in my system at all. Good luck with your search!
Fabulous and specific rundown on all the key components of a very nice system design and assembly in the past posts listing. Thanks for this listing of parts and sources.
Now had you priced out and totaled all the parts from the specific sources quoted, You would send many here, especially the newbies and fusion hopefuls into a very deep depression, if not abandonment of .... "all hope ye who enter".
Sticker shock, even at the lowest level of attainment, is best absorbed in stages of the effort. At the end of a successful trail to do fusion, one often wonders how they did it, if they total up everything they had to obtain to do the job. I know I did, and am still running up the bill since 1997 and my inspiration to build that first fusor I demo back then.
Have heart, It is only slightly more difficult than most can possibly imagine!
Do not let the price total of the above excellent listing be you guide as some here are able to use a nice, healthy. disposable income to do what this list suggests. Some of us got th' green, th' will and th' right stuff, to glide right through the monetary roadblocks.
You may envy them, but have to honor them when they succeed. They have shown us that they spent the time to learn and physically apply what they learn, as must we all, money be damned.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
lanewaddell wrote: ↑Tue Jul 30, 2024 9:39 am
Hey Ryan,
Where did you put in your pressure sensor(s) on this setup?
Thanks!
If you go back in my posts here, you will see a valve diagram that also has the positions of the vacuum gauges. The "CG" gauges are the Convection Gauges that measure the pressure on the rough side of the vacuum. The "IG" gauge is a cold-cathode ionization gauge that only starts to work when below a certain pressure. I changed the position of CG2 to be on the turbo side of the valve just so I can have a reading of the turbo when the system is off.
It is important to make sure that the high vacuum gauge is not in line-of-sight of the inner grid, as the ions can mess with the reading or at worst, destroy the sensitive and expensive gauge. I know this because in my first setup, I placed the ion gauge at the end of the long axis of my chamber (which normally forms the strongest beam if aligned correctly), and my readings jumped all over the place before I shut it down. Needless to say, I had the facepalm realization that it was in the beam, then moved it to where it is now.
Placement of the ionization vacuum gauge before (Left) and current (Right) with the long axis of the chamber highlighted in green. All three vacuum gauges are in yellow.
You can see that in my initial setup, the inner workings of the ionization gauge is directly in line with the beam formed in the long axis of my chamber at the top of the image on the left. I moved it so that it would no longer be in the beam and placed a Conflat blank at the end, which gives a lot of metal for the beam to dissipate its heat. In testing, the pressure does not jump all over when the plasma is formed.
This is great information. Especially the bit about not putting them in line with the main flow of gas.
Your gas inlet side is pretty large bore, I'm guessing because this is the side with the roughing pump connection?
I'm planning on piping d2 from a lecture bottle into a sawgeloc needle valve and then into a small (maybe kf16) tee and then directly into the chamber using a kf16 to CF 100 flange.
I was thinking one pressure sensor could come off the KF 16 tee on the perpendicular side and a similar setup using a Kf16 tee could be used on the vacuum pump side of my setup.
That way you are monitoring pressure at the gas inlet side and the vacuum side from a small kf 16 tee off the perpendicular right before entering the chamber.
The inlet for D2 into my chamber (1/2" Swagelok) is big because that's what I was able to find on eBay for a reasonable price. I used some fittings to reduce it down to 1/4" so I could connect a common refrigerator 1/4" copper line all the way to the operator station, where its reduced down to 1/8" for the connection to the D2. It doesn't matter how close it is to the rough pump valve since it will have long been closed off before D2 is ever introduced into the system and is only open when pumping down from atmospheric pressure.
I am not sure how big of a difference it would make in the molecular flow regime, but I felt uneasy about putting the D2 inlet right next to the high vacuum pump flange for fear of pumping out D2 before it could enter the main chamber cross. I placed it on the opposite side because I thought that any D2 that will leave the system will have to pass right next to the inner grid to get to the high vacuum pump.
You might be implying this, but to be safe I will make sure to tell you that you need a good pressure regulator or two on the D2 lecture bottle before it ever goes into the needle valve and the rest of the system. You do not want highly pressurized gas entering a vacuum, which is a way people make air cannons that get baseballs to go supersonic with air pressure alone. Please refer to the FAQ's for lecture bottle setups. I cannot speak to the proper construction because I am using a PEM cell and heavy water, which has the D2 gas at ambient pressure for my setup.
I would highly suggest either drawing a detailed schematic of your setup, or create a 3D model. Autodesk Fusion360 is a CAD software that has a free hobbyist version that I use. It is very important that you have something to put all of your parts together on paper or CAD before you physically do it. You will find problems with your setup and be able to fix them before you go out and spend significant money on parts that you can't use. If you haven't used Fusion360 before, it should be an easy project because you can just import all the 3D files from Kurt-Lesker's catalog online for free and you can mess around with the placement. Also I would suggest the New User Chat Area for design help on your specific system, since I am not an expert by any means.
Yes thank you! This is all great information. I think I've learned what I can from you without bugging you....so I appreciate all the help. I'm going to hit the books some more and I hope to make some real progress in the design space this weekend. I am also using Fusion 360 but I am farrrrr from an expert there.
No problem at all, I hope this information proves useful. If I see anything I can help with in the New User Chat Area, I'll post any tips or suggestions I may have. There are many incredibly knowledgeable people here with a lot of experience, but I am also fairly new to building a fusor, so I do not want to accidentally mislead you by my own inexperience.
I will add that the location of the input for the deuterium gas is not important. The gas molecules move at faster than commercial jet aircraft speeds so it tends to fill the chamber no matter where it is entering regardless of the pumping port location. Yet, why not locate it where you want when designing a system?
A lecture bottle must have a dual regulator as Ryan said and a good microvalve would be nice (through can be expensive.) Using capillary tubing like Ryan suggested is an old stand by to reduce flow rates. Adding tiny pin holes is another trick when combined with a normal needle valve.
Ignorance is what we all experience until we make an effort to learn
thanks!
