Archived - Fusor Update

[Scott Moroch]

I am very pleased to announce that I won Ben Krasnow's diffusion pump give-away contest. Here is the link to the contest: http://www.youtube.com/watch?v=W5B5mj6-fqk

Jack and I's original plan was to borrow Connor Givan's pump, and then potentially buy it from him. However, we were never completely positive if we were going to be able to buy the pump from him, so, I entered this contest. So now whether we are able to buy his pump or not, we will always have one.

For testing of our fusor we will be using Connor's pump because I already have the ASA fitting and adapters and oil to use his pump, so it is basically ready to be used. Also, the pump I won has a weird fitting which I will need to machine an adapter for.

Nevertheless, I am very excited to have won the pump. With the Varian air cooled diffusion pump I also receive o-rings, a custom built baffle, and 130 milliliters of DC 704 pump oil.

Scott Moroch

[Richard Hull]

Air cooled diff pumps are the bread and butter of successful, rapidly assembled fusor systems. No water, no drain and no liquid nitrogen needed for a trap. A quick trip to 10e-4 or 10e-5torr vacuums even with a moderately functional forepump.....Assuming all is done correctly.

Richard Hull

[Dennis P Brown]

Very nice photo's that go along with your progress. Hope you get a plasma test soon.

[Scott Moroch]

Thank you. We are very close. We just need one more KF fitting and clamp and to clean our 5-way cross in acetone, and then we will be ready to test demo mode. We will start with a smaller 6kv rectified NST when we do test. It has been a great experience so far and I really look forward to what comes in the future.

Scott Moroch

[Dave Xanatos]

Scott - what size KF fitting do you need? I just bought a wad on ebay...

[Scott Moroch]

I currently need a KF 50 to KF 16 reducer to go on top of the ASA fitting I have for the 6" diffusion pump. I also need a KF 50 clamp and o-ring.

Scott Moroch

[Scott Moroch]

Yesterday I received the air cooled diffusion pump I won. It included the pump, o rings, 130 milliliters of diffusion pump oil, and a custom built water cooled baffle. I will need to have a fitting made for the pump and figure out how to use the water cooled baffle. I will also need to get a fan for the pump

[John Futter]

Or
Heisenberg may have said
This may be good but i'm not certain


best of luck it looks like a reasonable deal

[Scott Moroch]

Over the last couple of weeks Jack and I have been getting our system ready for demo mode. Yesterday we assembled the entire system to test for vacuum. We are having major leak problems. We know we are pulling a very weak vacuum in our chamber. After we shut off the pump, we unclamped one of the KF fittings and heard some air rush back into the chamber. However, our thermocouple gauge is barely moving. The motor and the belt on the pump also sound slow like they are moving slow.

Also, our diffusion pump requires a 5CFM backing up, however we do not know the model of our pump. We know it is a Welch Belt Driven Mechanical pump but there is no model number on it and it did not say on the ebay listing when we purchased it. It weighs about 75-80 pounds and we are going to test it with a thermocouple gauge. Do you think if this pump can reach 10-20 milliTorr it will be good for our diffusion pump and fusor?

Just as a back up we do have a 5CFM refrigeration service vacuum pump. I would much rather use the welch but at least we have a Plan-B pump.

I have attached some images of our progress.

Scott Moroch

[Richard Hull]

Put the TC gauge on the inlet of the Welch and tell us what it reads. Are you sure the gauge is working and in good order?

Richard Hull

[Scott Moroch]

Yes the gauge is in working order. Our biggest problem is getting a good seal on the inlet of the pump. I hope it can pump down to the range we need it to. I have tested the gauge on my refrigeration service vacuum pump just to make sure it worked and it quickly got down to about 150 millitorr.

Scott Moroch

[Richard Hull]

Any good pump with a simple but good seal at the head with a TC gauge attached there, should almost immediately yank a good TC gauge down to under 50 microns and in one minute to about 30 microns or better.

This assumes good, new oil that is not water logged.

Richard Hull

[Scott Moroch]

We will work on getting a moderate to good seal on the inlet and then testing it with a thermocouple gauge to make sure its a good, working pump. If it isn't I guess it's back to ebay or the trading post.

Scott

[Richard Hull]

The general rule is that most e-bay sellers have only something for sale; beyond that, they don't seem to have a clue about much of anything else. A good maxim is to only buy a pump from someone very knowledgable and who can report a measured low end micron value. Some may quote the name plate which means nothing whatsoever or they report in inches of vacuum, which means they know nothing about vacuum or the pump.

Richard Hull

[Scott Moroch]

Thanks for all your advice Richard, its always helpful. I am going to test both my refrigeration service pump and the welch this weekend with the TC gauge. I will either report back here with good news or you will see a post in the trading post sub-forum. Looking for a pump from someone on here seems to be the way to go. What you said about ebay is very true.

Scott Moroch

[Scott Moroch]

Jack and I have spent the past week trying to figure out if we should use a needle valve for our fusor or not. I was reading through other posts thoughout the forum history and Steven Sesselmann mentioned that he had trouble controlling the pressure in his small chamber when he used a swagelok needle valve. I am worried that with our small chamber we may trouble with even the finest needle valve swagelok makes.

I have been looking into other solutions with orifices. I was looking at something like this: http://www.lenoxlaser.com/index.php?dis ... uct_id=107

I was wondering if anyone had an idea of what flow control would work best with our small size chamber. I know Chris recommends we use orifices. I would buy either the valve or orifice, however I want to buy the one that would work best for our system.

Would the round side of that tube, as seen in the link, work with a swagelok tube fitting?

Thank you for your help. I also realize that this post belongs in the Fusor Construction and Operation Subforum. I will gadly move it if an admin wishes me to. I just like to keep everything on our specific project under one thread for organization purposes.

Scott Moroch

[Richard Hull]

This one posting it getting a bit long. If you need advice on any subject and need a running discussion, put it in the appropriate forum covering that topic. Image du jour is simple a statement of progress or accomplishment and must always be acompanied by images. It is not a rolling discussion related to problem solving.

Richard Hull

[Jake Wells]

Chris Bradley shows you how to biuld an orifice using a needle placed on sheet rubber sitting on top of NW16/NW10 flanges.



viewtopic.php?f=6&t=3224

[Scott Moroch]

Thank you Jake. I have seen this post and it is a very interesting method. However, I have decided to go with an orifice from lenox laser. I have seen a lot of success with them in the forum: http://www.lenoxlaser.com/index.php?dis ... uct_id=117

That 1/4" tube would fit right into the swagelok fittings we have. Thank you though.

Scott Moroch

[Scott Moroch]

It has been a while since I have made an update on our progress. I have been trying to limit the number of posts I do to keep this thread short, however I figured an update is needed. Recently Jack and I have been working hard to find and fix the leaks in our system (It's a real pain!!). Everything has been ready to go for demo mode and we will see plasma as soon as all of our leaks are fixed.

Jack recently attended HEAS which I heard was great and I am dissapointed I was unable to attend. Jack bought a couple of goodies from Richard including an Eberline PNC-1 and a needle valve for gas control.

Jake Hecla pointed out to us that the NST and multiplier might not provide enough current and, as we knew, is incredibly dangerous. He recommended that we search for a more reliable power supply that will be suitable for a fusor. I have been looking on ebay for a while now and I have been having trouble. Usually the power supplies that I find are at the right voltage level, but the current is too low, or the voltage is too low and the current is too high.

Luckily, I recently found a Glassman -40kv 7.5ma Series ML power supply. This is the same series power supply that Will Jack used on his fusor, except his was 30kv at 10ma. The power supply does require that we wire a controller in order to operate it, however the manual includes all of the information necessary for this.

Scott Moroch