How hot do the temperatures on the top and bottom of the fus

Pavle Mihajlovic · Post by **Pavle Mihajlovic** » Tue Mar 25, 2014 1:39 am

I am wondering as I need to know what metal I should cast it with. I am 12 years old and hoping to be the youngest in the neutron club.

Jerry Biehler · Post by **Jerry Biehler** » Tue Mar 25, 2014 2:12 am

Cast? As in pouring liquid metal into a mold, casting?

Casting is not recommended for vacuum systems. It outgasses like you cant believe.

Pavle Mihajlovic · Post by **Pavle Mihajlovic** » Tue Mar 25, 2014 10:43 am

Yes but I will have a couple other systems to prevent that, and I do not have the necessary power tools to do it any other way

Chris Bradley · Post by **Chris Bradley** » Tue Mar 25, 2014 11:02 am

No one has cast their fusor shell (AFAIK), so if that is the route you pick for yourself, you are on your own and no-one can give you advice.

It is a crazy high-effort venture when there are such cheap alternatives to buy a chamber, or simply some of the larger vacuum fittings that will perform adequately.

Do you cast your own kitchen tools, frying pans, kettles, and such? I would expect you buy them, it is cheaper. Same with vacuum equipment.

Post by **Richard Hull** » Tue Mar 25, 2014 12:11 pm

I am curious. What metal or alloy were you considering? If I were forced against my better judgement to cast I would probably choose a copper-tin alloy like speculum Avoid alloys that don't cast to a smooth, ready you use finish. Avoid any alloys using metals that have a high vapor pressure above 600 deg C. I am intriqued by your boldness. You would be the first to ever cast a chamber. No help here other than the admonition about not using high vapor pressure metals and whatever you cast must never have pits and voids in the finished product.

Richard Hull

Pavle Mihajlovic · Post by **Pavle Mihajlovic** » Tue Mar 25, 2014 6:31 pm

Ok I may be reconsidering the casting, but are there any services which can drill specific holes where and how big you want them?

Tom McCarthy · Post by **Tom McCarthy** » Tue Mar 25, 2014 7:04 pm

Yes, there are many different procedures available, they all depend on how much you can spend and what material you will be drilling. However, if you are abandoning the casting idea and going with a stainless steel shell, the best for this would most likely be CNC drilling if you can get access to it.

Tom

Pavle Mihajlovic · Post by **Pavle Mihajlovic** » Sat Jul 05, 2014 2:27 am

This is a very late reply but where could I buy a viable chamber itself?

I am starting to get back onto the formus because I have sufficient finding

Dennis P Brown · Post by **Dennis P Brown** » Sat Jul 05, 2014 1:56 pm

Besides ebay, some people post here from time to time. When someone here posts it will have a good and useful selection of pre-flanged ports that work with most instruments/pumps. Ebay can be hard to get a system that is "off-the-self" ready. But deals exist if you can do some work or know where to get some SS high vac welding/cutting done.

As for youngest fusor ...first focus on getting a demo fusor working. The issue of deuterium, neutron detector, and the require and extremely dangerous power supply are major issues to address before one considers a real chamber.

Andrew Robinson · Post by **Andrew Robinson** » Mon Jul 07, 2014 11:36 am

Pavle,

You seem to be missing some really basic concepts here, all of which are easily answered by reading the FAQs. I highly suggest follow in the footsteps most everyone on this forum has done at one point or another and spend a huge chunk of time just reading as much as you can. Good luck.

Andrew Seltzman · Post by **Andrew Seltzman** » Mon Jul 07, 2014 11:05 pm

For your intrest on casting vacuum chambers, it can be done and done well. The toroidal vacuum chamber for MST at UW madison is cast aluminum, and we get vacuums in the 1E-7 to 1E-8 torr range. Recently the madison plasma dynamo was constructed out of a 9 foot diameter cast aluminum sphere.

http://plasma.physics.wisc.edu/mpdx
http://www.news.wisc.edu/newsphotos/dynamo11.html

For a fusor, just buy a stainless hemisphere though.

Rich Feldman · Post by **Rich Feldman** » Tue Jul 08, 2014 1:53 pm

Very nice, Andrew, thanks for sharing. Quite the molding project for a one-off part. Biggest core I've ever seen. I wonder what alloy was used?

I bet that success with the smaller chamber helped to get approval for the 3-meter one.

As for why not a stainless steel weldment, do you know if magnetic field perturbations were a consideration?
Long ago I worked on the magnetometer boom for Voyager spacecraft.
Even "nonmagnetic" stainless steel can develop unwanted magnetic permeability
from cold working and welding, and it would not be cheap to anneal a 3 meter hemisphere.
http://www.cartech.com/techarticles.aspx?id=1476

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How hot do the temperatures on the top and bottom of the fus

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