Usable Diffusion Pump?

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Miles Hawley
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Joined: Sun May 13, 2018 7:32 pm
Real name: Miles Hawley

Usable Diffusion Pump?

Post by Miles Hawley » Thu May 17, 2018 10:03 pm

Hi,

I was surfing ebay for a diffusion pump and stumbled upon this pump, will this work as a diffusion pump for fusion. https://www.ebay.com/itm/Varian-0160-La ... SwhBhazs-4

Also found another one: https://www.ebay.com/itm/Edwards-B72201 ... Swydpa8xUP

If someone could inform me asap if these pumps would be sufficient for fusion, price doesn't matter to me in this case.

-Miles

Adam Binns
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Real name: Adam Binns
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Re: Usable Diffusion Pump?

Post by Adam Binns » Fri May 18, 2018 2:30 am

the first pump has no mains input cable and the input voltage is not listed.
the second is the same and does not have a controller.
with some research and some spare parts, you might be able to get one of these to work but you would probably be better off finding a pump with the necessary components.
"it's not illegal just don't get caught"

Miles Hawley
Posts: 14
Joined: Sun May 13, 2018 7:32 pm
Real name: Miles Hawley

Re: Usable Diffusion Pump?

Post by Miles Hawley » Fri May 18, 2018 2:41 am

Thanks for the response, I suppose ill keep looking around.

-Miles

Michael Bretti
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Re: Usable Diffusion Pump?

Post by Michael Bretti » Fri May 18, 2018 4:03 am

The first pump does have a mains voltage listed - if you look at the picture it says 120 volts, 450 watts. A 5 second search on google also turns up this datasheet for the specs for various diffusion pump models. This one is a Varian 0160 - in the attached datasheet below, on page 6 in the second column, you will find the basic specs for this exact pump. This will give you all of the major specs you need to run it if you decide to go for this pump. Diffusion pumps also do not need a controller - just connect it to mains power with the proper fluid fill, water cooling, and foreline pump.

Varian Diffusion Pumps.pdf
(1.69 MiB) Downloaded 15 times

Again, another quick search on google will yield the datasheet specs for the turbopump as well. On page 6 of the below datasheet, you will find the basic specs for this exact pump in your second link:

EXT Turbomolecular Pumps.pdf
(2.23 MiB) Downloaded 9 times

To answer your question, if the pumps are in good shape, then yes, either will work fine for fusion. For the diffusion pump in the first link, it is a very simple device to get up and running. The power cable is cut but that is trivial - you would just open up the heat shield on the bottom, and rewire a new power cable to the heater. The second pump, a turbopump, will require some sort of controller. There are advantages and disadvantages for each of these types of pumps. I would suggest doing thorough research and understanding the basics of these pumps first before buying them. In terms of cost and ease of operation, diffusion pumps usually win. They are also incredibly robust and can take much more of a beating. The downside is that they don't run as "clean" as a turbopump, and a baffle is preferred, although a 90 degree elbow that is cooled can serve as a very effective baffle itself. However, that diffusion pump already has an adapter of some sort mounted to the top of it with what looks like 2.75" CF flanges, which makes your job significantly easier. You could just bolt your 2.75" CF cross chamber directly to that, though some sort of valve should be used between them for throttling, and even use the other port for some sort of vacuum gauge input. The top could easily be blanked off with a very simple aluminum plate and o-ring gasket if you don't need that spout at the top of the adapter. However, depending on what condition the diff pump is in, you may need to take it apart and clean it on the inside. Both pumps, from initial inspection, look to be in decent shape. The turbopump listing says it was removed from a working environment, but you always need to weigh the risks for these types of purchases. They are both very reasonably priced for their condition, it would be very hard to find high vacuum pumps for cheaper in good condition. I would say they both look like excellent options to consider.

Regardless of the pump you go with, there will be work involved to get it operational. If you want to do this type of science on a budget, you have to be willing to get your hands dirty and do it yourself. I wouldn't necessarily wait around to find the perfect pump with everything all ready for you - chances are you won't find it on the surplus market unless you are willing to spend a lot more money. Whether it is wiring, cleaning, etc, there will be some work involved. And the more you know ahead of time and research thoroughly, the more prepared you will be, and the higher your chances of success.

Miles Hawley
Posts: 14
Joined: Sun May 13, 2018 7:32 pm
Real name: Miles Hawley

Re: Usable Diffusion Pump?

Post by Miles Hawley » Fri May 18, 2018 6:52 pm

Good to know, thanks for the information.

-Miles

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