Leak in vacuum system (diffusion pump?)

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.
User avatar
Dennis P Brown
Posts: 1785
Joined: Sun May 20, 2012 2:46 pm
Real name: Dennis P Brown
Location: Glen Arm, MD

Re: Leak in vacuum system (diffusion pump?)

Post by Dennis P Brown » Tue Mar 31, 2020 10:36 am

While excess volume isn't desirable, the real killer for any system is the number and size of connections! This is where 99.9% of all leaks occur. Making good connections isn't always easy and leak checking is essential and not always easy; and even then, very minor leaks can occur (a damaged surface) require special methods that aren't easy to do.

Not that volume isn't a serious issue for any fusor - virtual leaks from the vast wall area is a killer, too. But for high vac systems (bake outs, inert gas flushing, and rare exposure to air) this isn't the problem for reasons given. Not so for most fusors. They are often open to the air, few have bake out abilities nor dry air flushing. As such, as Richards and others point out, large volume vacuum components aren't good.

The only way to deal with it is costly - adding bake out wraps, creating dry air flushing and good leak detection methods - in the short run, it is far less costly and easier to do as Richard suggests and get the adapter made to eliminate as much large volume parts as possible.

Thomas Sheeleigh
Posts: 10
Joined: Sun Mar 25, 2018 4:27 am
Real name: Thomas Sheeleigh

Re: Leak in vacuum system (diffusion pump?)

Post by Thomas Sheeleigh » Tue Mar 31, 2020 6:11 pm

I will write this first build down as a learning experience. Luckily, most of the fittings and hoses I have were bought used and cheap so although it is money wasted, it is not as much as it could have been. However, I am still not certain that there is no leak in my diffusion pump as I still haven't been able to make sense of that popping noise. I will have to inspect it more closely when I rebuild. Thanks again!

User avatar
Richard Hull
Moderator
Posts: 12088
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Leak in vacuum system (diffusion pump?)

Post by Richard Hull » Wed Apr 01, 2020 2:38 am

Not problem, first builds are always time consuming, costly and disappointing. Learning always involved time and treasure. It is the norm in vacuum work.

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.

Post Reply