Diffusion Pumps 101

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.
chad ramey
Posts: 105
Joined: Wed Apr 29, 2009 2:45 am
Real name: Chad Ramey
Location: Georgia
Contact:

Re: Diffusion Pumps 101: Jet Assembly

Post by chad ramey » Sun Jul 03, 2011 7:39 pm

Wow....just simply fantastic. The craftsmanship exemplified thus far is astonishing! I look forward to seeing how it works.

-Chad

George Schmermund
Posts: 262
Joined: Wed Aug 16, 2006 12:51 am
Real name: George Schmermund
Location: Carlsbad, CA

Re: Diffusion Pumps 101

Post by George Schmermund » Sun Jul 03, 2011 9:42 pm

The boiler section of the pump has been the easiest part so far. It took about 5 minutes to setup and braze a 1/4" SS bolt to the bottom of the pump body and another 10 minutes to cut up a vegetable can from the pantry and then put some holes and grommets in it. The trimmed can was used like a cookie cutter to make the Fiberfrax insulation pieces. The rope heater was wrapped flat against the bottom of the pump body and compressed into place by the lid from the can, which also had a hole in the center. This formed a sort of spool arrangement to keep the heater coils tight and flat. The leads were then fed through the grommets and the whole boiler assembly tightened up with the bottom nut.

More to come.
Attachments
DSCF1642.jpg
DSCF1642.jpg (126.69 KiB) Viewed 2320 times
DSCF1641.jpg
DSCF1641.jpg (182.53 KiB) Viewed 2320 times
Anything obvious in high vacuum is probably wrong.

richnormand
Posts: 288
Joined: Sat Aug 27, 2005 12:30 pm
Real name: rich normand

Re: Diffusion Pumps 101

Post by richnormand » Sun Jul 03, 2011 10:17 pm

Very, very nice George!
Can’t wait to see how well this will work out.

Most of the stuff seems to be stainless steel and such. Is the tin can part of the heater a possible problem? They (tin cans) tend to have coatings inside (plastics or flash metals) and soft welds at the seams that could be an issue even if it is not in the vacuum part of the pump? I assume your temp will be low so that is not such an issue.

Still, the eye candy value alone has me glued to the photos.

Looking at the inventiveness, particularly using common utensils, is in the best traditions of Rutherford's work and "Building scientific apparatus" first edition....

User avatar
Carl Willis
Posts: 2841
Joined: Thu Jul 26, 2001 11:33 pm
Real name: Carl Willis
Location: Albuquerque, New Mexico, USA
Contact:

Re: Diffusion Pumps 101: Jet Assembly

Post by Carl Willis » Mon Jul 04, 2011 2:04 am

Modern art with "found objects"! Nice work, George.

I can't wait to see the results of your trials. What will be your pumping fluid? Extra-virgin olive oil?

-Carl
Carl Willis
http://carlwillis.wordpress.com/
TEL: +1-505-412-3277

George Schmermund
Posts: 262
Joined: Wed Aug 16, 2006 12:51 am
Real name: George Schmermund
Location: Carlsbad, CA

Re: Diffusion Pumps 101

Post by George Schmermund » Mon Jul 04, 2011 7:46 pm

Thanks for all the encouragement, guys! If I get some time today I'll finish up the foreline and braze it into the pump body. The final effort will be to shape and install the cowling and cooling fan(s).

As far as the can used for the boiler heat shield goes, there is no seam, but there is a very thin coating on the inside surface. I'll carbonize the coating with the torch and then clean up the can with some Scotch-Brite and Lysol PTBC. I'll also probably add a thermocouple to the bottom of the boiler. This will allow me to run some temperature/ pressure curves in the future.

I do remember something about distilling olive oil and using it in a desperate act as a diffusion pump fluid. I think it was in The Amateur Scientist column back in about 1960 or so. Anyway, I'll stick to DC 704 for this project.
Anything obvious in high vacuum is probably wrong.

User avatar
Richard Hull
Moderator
Posts: 11961
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Diffusion Pumps 101

Post by Richard Hull » Tue Jul 05, 2011 2:02 pm

Looks like it ought to work. You have poured the work into it. If this works out it will offer a cheap way for the DIYs to make a small air cooled pump more suited to a small fusor rather than have to pay the premium often seen on these small manufactured units.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

User avatar
John Taylor
Posts: 97
Joined: Wed Jun 22, 2011 5:43 pm
Real name:
Location: Dardanelle, Arkansas

Re: Diffusion Pumps 101

Post by John Taylor » Tue Jul 05, 2011 4:13 pm

Very nice workmanship! I can't wait to hear how well it works, I would like to emulate this as it looks like a great project.

George Schmermund
Posts: 262
Joined: Wed Aug 16, 2006 12:51 am
Real name: George Schmermund
Location: Carlsbad, CA

Re: Diffusion Pumps 101

Post by George Schmermund » Tue Jul 05, 2011 8:56 pm

The pump body is basically finished at this point. Next is the cooling system. I've been thinking about different configurations and they all seem to have their own merits. I'll put a few thermocouples at the points where I'm interested in seeing the effects of the different methods.

I've added another pic of the boiler so that it's clear how the rope heater is installed and kept under control. It's important that the heater remain in intimate contact with the bottom of the boiler.

After torching the can to red heat to remove the plastic film on the inside and then Scotch-Brite scrubbing it clean, I decided to retorch it to get that 'gun metal blue' look. This is my concession to steampunking and Carl's comment about "art".
Attachments
DSCF1650.jpg
DSCF1650.jpg (141.53 KiB) Viewed 2320 times
DSCF1648.jpg
DSCF1648.jpg (145.73 KiB) Viewed 2320 times
Anything obvious in high vacuum is probably wrong.

richnormand
Posts: 288
Joined: Sat Aug 27, 2005 12:30 pm
Real name: rich normand

Re: Diffusion Pumps 101

Post by richnormand » Tue Jul 05, 2011 9:29 pm

Would one or two computer CPU fans with a metal shroud following the curve of the main body be adequate? If not a ThermalTake liquid CPU cooler might do, with a small copper tube spiral on the outside.. It comes with its own pump, radiator liquid-to-air heat exchanger and all the trimmings. I used them for cooled pmts, peltier cooled ccd detectors and ccd camera. The old models are available on ebay for cheap and can displace lots of heat in a small turn-key package.

DaveC
Posts: 2346
Joined: Sat Jun 30, 2001 5:13 am
Real name:

Re: Diffusion Pumps 101

Post by DaveC » Wed Jul 06, 2011 1:02 am

George - beautiful!

You combine, art, science, practical engineering and a great sense of humor. Impressive work.

(Lots of real talent amongst those on this board.)

Dave Cooper

Post Reply