Diff pump

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
Jgn1
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Re: Diff pump

Post by Jgn1 » Wed May 23, 2012 12:27 pm


Thanks for the info!

I manage to get the price down to 950 pounds.

did you read that the XDS10 scroll pump is not included, but only the Turbo pump and controller?

I'm about to confirm it, but I want to be sure that I wont regret it, haha.

Tyler Christensen
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Re: Diff pump

Post by Tyler Christensen » Wed May 23, 2012 12:30 pm

That's an awful lot of money for a turbo pump on ebay. They frequently come up for under $100 without a controller, which could be purchased separately or pretty easily made yourself if you know anything about electronics. In fact I'm pretty sure there are some <$100 turbos up right now, someone recently posted about them.

I wouldn't even begin to consider spending this much money for an ebay turbo myself.

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Dennis P Brown
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Re: Diff pump

Post by Dennis P Brown » Wed May 23, 2012 12:52 pm

Sorry to hear that the main pump is not included and really, they are not selling the entire system - that makes the deal way over priced. I fully aggree with Tyler - look for pumps on e-bay and pass this one up.

Edit: I would like to add - a turbo (if obtained cheaply is well worth the effort) is nice but what are you aiming for? A fusor that demonstrates all but neutron production or one that produces neutrons? Remember, the primary pump (roughing) and some type of vacuum gauge with a chamber and all connecting vacuum components are the main items you will need to get started. One major issue to consider is what level of power (the HV system determines if it is a neutron producing fusor or not) you are trying for? A turbo or diff. pump are secondary issues compared to all of this and should not eat up most your budget!

The issue is really what are you trying to achieve and the time frame - for instance; buying a chamber (some vacuum SS chamber) is one of your main issues to be addressed. Feed thrus and what and how you will do that is far more important than a turbo pump because as most can tell you here, depending on the approch, that can be a big $$$.

This is purely my two cents but I have been collecting stuff for a fusor but have not tried for a power supply because I have not seen one that I feel is worth the cost/effort/gamble. Of course, I am not trying very hard since I am focused on a linear accel. and production of neutrons (if I am lucky!)

Jgn1
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Re: Diff pump

Post by Jgn1 » Wed May 23, 2012 1:54 pm

Thanks for the advice!

I just want to learn as much as I can. That's the goal. I'm just a student. But eventually, with more experience, I would like to make experiments and also try my own designs, taking optimization into account. I would like to try everything within my reach - I'm also interested in linear accelerators.

I'm currently waiting for my primary pump to come. It's an Edwards (number 5). Two days ago I bought two hemispheres of stainless steel, with a diameter of 25 cm. They were very expensive. I'm still missing the Vacuum gauge and the connecting vacuum components. I plan to do that probably on the weekend.

I still need to read a lot about the "theory" of the fusor. I'm planing to resume my readings also on the weekend - on thurday and friday, I have 4 tests to do at college.

I'm spending all my savings, and I don't care - but that doesn't mean to spend money innecessarily!

I'll go for a DP.

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Dennis P Brown
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Re: Diff pump

Post by Dennis P Brown » Wed May 23, 2012 2:34 pm

I have no where near the experience/knowledge of many of the people here and I am just using what I learned putting together my accelerator project. But for vacuum systems you really need to make some important decisions at the very start or you risk wasting a ton of money – what type of connector system will be used for the vacuum support system? All SS? I had to go that route because I am trying for 10-6 torr (so that regular bottom 10-5 torr is trivial to achieve) but fusors are different - they work in the micron range.

Since fusors do not need levels of vacuum below one micron, both copper and/or thick walled plastic/rubber vacuum grade tubing is fine for many parts. These types of ‘tubing’ systems are hard at times to interface with standard SS flanges/connectors and that is the main issue for people who go that rount. Not impossible to do – my DP fore line to SS quick flange system is a short piece of vacuum grade rubber tubing. Just realize that off standard stuff can kill a project unless you can machine around the issue or put up more cash to interface these components.

Quick flange (use a K for quick; so really KF) connectors are great and the standard 25 mm diameter (KF-25) is perfect for most easy to get items. The Chinese sell the required o-ring and clamps dirt-cheap and I bought a six head 20 mm KF octopus rig for 1/3 the price I saw everywhere else and the workmanship was ultra high quality.

That all said, valves and electrodes are really high end costs that many just overlook at first before laying out their system in detail. These components are critical to have (and think carefully on the vacuum system design; otherwise, you buy stuff that turns out to be of no use!)

It is best to search e-bay and look for deals on these items - I got some great deals on vacuum valves BUT they all had issues and needed work. Otherwise, you waste a lot of funds and end up with expensive scrape! Remember, leak checking is not easy and gross leaks will kill any fusor project. I did much of my building effort dealing with leaks but again, I am at a very high vacuum range.

From what you are saying, I'd think your next major item to watch for and CAREFULLY price it relative to performance before buying it (they list the requirements here in the forum) is a good x-ray transformer. Such a transformer has to be the correct power/voltage or fusion is impossible. Remember, these voltages/currents are lethal and you need to deal with that – you get no second chances. That is why I am hyper fearful/careful of the x-rays that could be produced by my system. The voltages a fusor uses can also produce dangerous fluxes of x-rays, too.

Best of luck and this is really a great forum with really knowledgeable people who have so much working hand skills.

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Re: Diff pump

Post by Jgn1 » Wed May 23, 2012 3:21 pm

Your info is very appreciated!

I really don't know what exactly you refer with "what type of connector system will be used for the vacuum support system?". (Note: I'm quite a newbie.) Do you mean the connectors around the chamber? If yes: yeah, all SS; that's the plan. I would like to use this chamber for other things too, not only for the fusor. What exactly? I don't know, but I think something else can be done. Time will tell.

I'll take note about your suggestions for the flanges. I actually plan to design how they are going to be distributted and plugged into the chamber - the order doesn't matter, right?

I plan to use a TIG welding rod, as the electrode. Is that fine? I have no idea about the valves, only that they are expensive.

I still haven't read anything abouth the X-ray transformer. I plan to read first about it, and then search for it.

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Dennis P Brown
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Re: Diff pump

Post by Dennis P Brown » Wed May 23, 2012 3:48 pm

I am in no way knowledgeable about fusors - do read up here on the forum and ask the experts here.

What I was saying about ‘connecting system’ is how do you plan to connect a roughing pump to the chamber with a vacuum gauge somewhere in between? Also, how to later install a DP/or turbo and this, in turn, then to the chamber? Gate values to throttle? And so many other things like electrical feed thrus.

If you look at my linear accelerator support system, 70% of the volume and 90% of my cost is simply vacuum connection stuff – SS ‘bellow’ lines, valves, clamps, QF elbows, four way KF, and the list does on. Having a roughing pump and chamber are the backbone of a fusor but how these get connected together is the $$$ question. I use quick flanges (KF) because they are simple, can be found every were, are great for low/high vac and most all types of SS flanges feed thru's (electrical both high current or high voltage, vacuum pump ports or accessories, etc) come in versions that use KF. Jut be careful – many off size QF are out there and many cheap flanges/adapters are also off-size; hence they’re cheap. But wait until you price adapters and the savings vanish.

Quick edit: issues about system location. Where will the system be run? Appartment buildings may be very questionable esp. the line power for an x-ray transformer and issues of radiation (x-ray but also neutrons for high end fusors.) Note that my entire accelerator system is installed on a cart to allow placement or removal (but a single 120 outlet handles all my power needs - total system runs under 10 amps. A fusor can be far worse.) With a cart, I had to carefully layout the design ahead of time if I wanted everything to align up and fit in the available space (including for me, heavy shielding.) Just saying that such a minor point is often overlooked but it can kill a project if not considered.

One thing I will warn against just from my experience – this may not apply to you - don't double up uses for the chamber. The fastest way to fail is to try and build two or more systems in the same chamber (Fusor, metal coater, plasma asher or what-ever.) You more often than not waste time, money and get frustrated by minor issues. My two cents but I have built many operating vacuum based systems previously and have learned the hard way.

One final word - avoid jury-rigging any high voltage system to adapt to a chamber. Anything that is high voltage (and carries any real current) should use proper connectors (read proper wire insulation), feed thru’s (made for the voltage/current.) Cutting corners here is asking for electrocution.

Jgn1
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Re: Diff pump

Post by Jgn1 » Wed May 23, 2012 4:28 pm

I'm still figuring out how I'm going to do the connection system. Currently I don't know... No idea.

What's wrong when you make your chamber an hybrid system?

I'll take special care to the hazards. The whole idea is not to create the machine that will kill you!

Quick edit: well, I'm doing all this in my flat - in the kitchen...

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Dennis P Brown
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Re: Diff pump

Post by Dennis P Brown » Wed May 23, 2012 5:37 pm

Again, I am no expert on fusors but when you ask:
"What's wrong when you make your chamber an hybrid system?"

My point is that different applications generally require different feed ins, vacuum connectors, ion guns(s), gauges or viewing ports, etc all in one chamber. Some of these may block space for fusor items and some applications may create contaminates that would cause issues for one or both or all other systems. A lot of unknowns, added to already a complex and possibly dangerous system.

It would make more sense to install a vacuum system with gauge controllers on a movable cart and build a chamber for each application. Any given application, say the fusor, would have its required gauge sensors and high voltage systems already in place. You'd just connect the vacuum system to it. After getting done, roll the vac system to the next chamber/experiement. Again, just my two cents after many, many years of experience with these types of systems.

Late edit: remember, some applications do not require steel chambers (even fusors) and glass and other housing can work depending on what you are trying to do. Most just require an chamber that allows some degree of vacuum.

I did design my system on a cart with wheels so it can also be connected to a fusor that would be in a fixed location a bit away. Many fusors have heavy and very dangerous (ie need proper wiring/shields) electrical systems that are best left in place.

Your call on how best to use your chamber but I'm at a lost on what else a fusor chamber would also work as ... . Your device. your call.

Best of luck.

Jgn1
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Re: Diff pump

Post by Jgn1 » Wed May 23, 2012 8:44 pm

I really like your idea of the table with wheels. I definitely will do that.

Some days ago I saw this (pic atached) plastic (PC) container which is supposed to be a lamp and I bought it. I though that it would be perfect for a Vacuum chamber. You think it's possible to create fussion inside this plastic container? And if I want to put ion guns, no problem?

The other pics correspond to the two hemispheres of SS that I bought.

I'm currently looking for the Vacuum gauge and a controller. Does the Varian 860A controller is ok? If yes, any suggestion for the Gauge?

What's a "CVC Discharge vacuum guage tube cat. no. GPH-001A for high vac". And CVC tubes?

Quick edit: I took the photo with my laptop - I don't have a camera and I don't have a mobile...
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