Fusor Forums

Been lurking for a year, got hooked after seeing one in action, so I guess I have to make one myself now.

Got a Pyrex 6947 1000ml container with flange:
http://www.members.aol.com/rscopper/belljar.jpg

Made some grids:
http://www.members.aol.com/rscopper/grids1.jpg

Dug up a pump:
http://www.members.aol.com/rscopper/pump.jpg

Update 3/27/04:
System complete - you were right, not enough vac.
http://www.members.aol.com/rscopper/complete.jpg
http://www.members.aol.com/rscopper/complete2.jpg

Found someone who has an "extra" 2-stage pump and micron-meter - have to do some heavy bartering for this one though.

R. Scott

Note: I have archived this image and several others following this one to show how the vacuum improved with first a new pump and techniques over a very short time. There are images of really bad vacuums and the final one of a very good vacuum with all the stages in between. It is a good teaching tool and visual examples of various vacuum levels and should help out a lot of newbies with demo system analysis.

Richard Hull

New pump and gauge!

O.K. What am I doing wrong here? Is this still not enough vacuum?

Success!

I got the best vacuum by just cleaning the glass real good and sticking it right to the aluminum with a bit of silicone stopcock grease.

Not sure, didn't have the sensor plumbed in. After another day of screwing around, I figured out that my spark plug feedthrough is leaking! If I take it out and stuff some rubber in the hole, the pressure drops like a rock. So.....I got the pump working good, I got the chamber sealed well, got to go out tomorrow and get me some more spark plugs. I must have broken the seal between the ceramic and the electrode or the case when I chucked it in the lathe to cut off the threads. (don't know my own strength - as bullwinkle used to say)

Made a new spiral inside grid out of stainless, and a new spiral outside grid out of 1/8in copper tubing - looks cool. Put some neodymium alloy magnets inside the inner grid, and they demagnetized in about 2 minutes! I was only running at <500V at the time. I had them stuck together pinching the top of the grid, and they just fell off. What do you think? Heat? or Eddy currents?

Sooner or later I'll get this thing licked......having fun with my new toy...

Scott

Made a new spark plug feedthrough this morning with an o-ring seat. The best vacuum I can get after about an hour of pumpdown is 250 micron. The best I've gotten out of this pump with the gauge right on the pump outlet is 150 micron. Here's a pic at 250 micron at about 400VDC half wave rectified with 0.15uf filter cap.

I think I'll work on different shapes of grids next.

Scott

I am building the demo fusor into a new box so it's more portable. My brother gave me some of this cool aluminum coated plastic - you just make two 45 degree cuts just through the plastic to the edge of the aluminum with a table saw - then bend into a box. It's very strong and looks professional.

Scott

The port-a-fusor is complete. Had some nasty vibration problems mounting the pump in the box - had to use some SS braided hose in the vacuum line to reduce the vibration.

Looks really good scott. Whats your lowest attained vacuum level ?

Mark Rowley