Is bigger better?

For posts specifically relating to fusor design, construction, and operation.
Post Reply
Russ Gaines
Posts: 20
Joined: Fri Mar 07, 2014 3:39 pm
Real name: Russ Gaines
Location: NC, USA
Contact:

Is bigger better?

Post by Russ Gaines » Sat May 17, 2014 2:29 pm

I ditched the freon tank, it would have been cheaper to have a chamber custom made. I am now shopping for a chamber and was wondering, when it comes to chamber size, is bigger better?

Russ
Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality. -Nikola Tesla

User avatar
Richard Hull
Moderator
Posts: 12181
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Is bigger better?

Post by Richard Hull » Sat May 17, 2014 3:30 pm

No, it is worse! Bigger is very bad.

6" to 10" is ideal. Smaller and you might have high voltage electrical arc control issues, melting of smaller grids, etc. Larger and you will have to pump forever with a really good pumping system and waste a lot of valuable deuterium in such a huge volume.

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.

Russ Gaines
Posts: 20
Joined: Fri Mar 07, 2014 3:39 pm
Real name: Russ Gaines
Location: NC, USA
Contact:

Re: Is bigger better?

Post by Russ Gaines » Sat May 17, 2014 5:23 pm

Thanks Mr. Hull, that will be very good to know when searching for a chamber. That being said; one more question, would I have arcing issues in a real fusor with a chamber like this one? Image Its 2.75"
Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality. -Nikola Tesla

charlie_mccartney
Posts: 139
Joined: Sat Jun 29, 2013 7:45 pm
Real name: Charlie McCartney
Location: Dallas, Texas, U.S.A.
Contact:

Re: Is bigger better?

Post by charlie_mccartney » Sat May 17, 2014 7:49 pm

I am using that for my demo and I have had no melting issues with my SS grid or arcing issues at all.
Charlie McCartney
charlie.mccartney1104@gmail.com
charliespersonalproject.weebly.com

User avatar
Richard Hull
Moderator
Posts: 12181
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Is bigger better?

Post by Richard Hull » Sun May 18, 2014 5:30 am

Charlie is not doing fusion either, where voltages soar to 3 or 4 or more times the voltage in a demo device. Demo devices rarely exceed 50 watts while fusion devices often hit 300-500 watts. A big differrence on grid heating.

I do believe we have had a person do fusion in a 2.75 cross, but at a very low level due to all the constraints I mentioned.

If you are serious about fusion use 4" as a bare minimum and 10" as a working maximum diameter. The best fusors ever built here are 6" and 8" models. That speaks volumes.

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.

Alexandru_Calburean
Posts: 49
Joined: Fri Dec 06, 2013 2:30 am
Real name: Alexandru Calburean

Re: Is bigger better?

Post by Alexandru_Calburean » Sun May 18, 2014 4:15 pm

Russ,

I will also say this: my current setup is that of a conflat cross and I find that not even 20kV at ~30 microns will get it to light off. Unless there is something wrong with my data it seems that crosses are much harder to get lit because of the PXD part of Paschen's law and the how that plays with the long arms on the chamber. Fusion has indeed been done in such a setup by two people: Chad Ramey and Will Jack, so look them up if you want to see how they arranged things in their chamber. Such chambers are a minimum needed for fusion and as Richard said will only be doing fusion at a lower level, but for the amateur with a tight budget, the 2.75in CF cross is a godsend. Good luck in your attempts.

All the best,
~Alex Calburean

Richard Hester
Posts: 1458
Joined: Thu Jul 05, 2001 4:07 am
Real name:

Re: Is bigger better?

Post by Richard Hester » Sun May 18, 2014 9:49 pm

Actually the second amateur fusor (right after Richard Hull's and with a remarkably short assembly time,as all the bits were pretty much at hand) was done in a conflat cross ( a 6" cross, which would have a ~4" diameter tube) - check out Scott Little's archived data at earthtech.org. He used a small power supply (Plastic Capacitors, 20kV/10 ma), and got an estimated 10^4 neutrons/sec.

User avatar
Richard Hull
Moderator
Posts: 12181
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Is bigger better?

Post by Richard Hull » Mon May 19, 2014 1:11 pm

It must be remembered that in our early efforts, both Scott and I had very good neutron measuring instrumentation, something most amateur attempts today never have. The low neutron numbers of small or ill-run fusors typically demand superlative detection gear to prove fusion.

The number one failing of amateur fusion attempts is a failure to prove fusion and this, in turn, usually translates into poor to virtually non-extant neutron detection gear or very bad data collection techniques if such instrumentation is at hand.

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.

Russ Gaines
Posts: 20
Joined: Fri Mar 07, 2014 3:39 pm
Real name: Russ Gaines
Location: NC, USA
Contact:

Re: Is bigger better?

Post by Russ Gaines » Mon May 19, 2014 1:41 pm

I found a good 6" chamber on ebay I'm going to try to get, providing I can borrow some money from my dad.
Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality. -Nikola Tesla

Post Reply