Cube fusor build

For posts specifically relating to fusor design, construction, and operation.
User avatar
Richard Hull
Moderator
Posts: 12204
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Cube fusor build

Post by Richard Hull » Sat Oct 12, 2019 12:08 am

If I remember correctly, from my old readings, fusion of D-D via tunneling is perfectly isotropic and cares not a whit about the field conditions or original collisional directions. Anisotropy is more a function of reflection and scattering after the totally isotropic fusion event, itself. This makes sense as the original directions of the deuterons or fast neutrals are under 50kev. The reaction zone at the instant of fusion produces a net energy on the order of several meV. This swamps out any lower energy directional momentum plus any electric field conditions as far as the neutrons are concerned. The neutrons go wherever they want to and that nets out to isotropic emission.

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.

Jon Rosenstiel
Posts: 1391
Joined: Thu Jun 28, 2001 5:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Cube fusor build

Post by Jon Rosenstiel » Sat Oct 12, 2019 5:28 pm

Richard,

The reaction may be isotropic in nature, but the neutrons coming out of the cube are definitely not. Both Joe and I have confirmed that the cube's neutron "output" or "flux" is about four times stronger in line with the plasma beam than at right angles to the beam.

Jon Rosenstiel

User avatar
Richard Hull
Moderator
Posts: 12204
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Cube fusor build

Post by Richard Hull » Sat Oct 12, 2019 7:40 pm

If this is true then it points to the ion streamlines impacting possible buried deuterium on the end plugs. (A form of beam on target where the source of the reaction is not within the grid and perhaps not even in the ion streamlines.) Two fusion emission points. Worth looking into.

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.

Jon Rosenstiel
Posts: 1391
Joined: Thu Jun 28, 2001 5:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Cube fusor build

Post by Jon Rosenstiel » Sun Oct 27, 2019 11:58 pm

Titanium cathode testing. One of titanium's downsides is outgassing when it becomes red-hot.
Ti cathode_640_jpg.jpg
Ti cathode_640_jpg.jpg (39.36 KiB) Viewed 1530 times
Jon Rosenstiel

User avatar
Richard Hull
Moderator
Posts: 12204
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Cube fusor build

Post by Richard Hull » Mon Oct 28, 2019 3:49 am

Get yer red hots, right here!! The old call from vendors at ball games is apropos here. That is one hot Ti electrode.

Jon, guide me here with some of your long working wisdom and your current efforts and opinions with the cross/cube. I look at them as being one and the same.

How are the neutron numbers coming, Jon? Are they tough to get compared to your spherical system? I am about to take down fusor IV to monkey with the small CF cross idea. In your honest opinion, is it worth it for those who need neutrons? You are a solid guy with the good gear like only a few of us possess. Talk candidly here as I do not seek a new path for the sake of newness, nor am I just looking for a first pass win like so many newbies. I like neutrons and not fusion. Unfortunately, fusion is a route to obtaining those neuts. Do you think it is a good idea to cast off the old working system in favor of the cross if neutrons are the criteria?

While the cross can be an easy in for doing fusion and proving it at the newbie level, is it a real good neutron producer.

If a mega mark is tough for you to reach in the small system, I will still dismantle fusor IV and totally revamp the system to a much needed upgrade from the old 2004 original build. For the foreseeable future, I am voltage limited to 45kv max with 40kv more likely to be my limit. As you know, I struggle to get, but regularly do get, 10e6 neutrons or a bit more with luck and several days of "run in".

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.

Jon Rosenstiel
Posts: 1391
Joined: Thu Jun 28, 2001 5:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Cube fusor build

Post by Jon Rosenstiel » Mon Oct 28, 2019 6:09 pm

Richard,

I'll have some answers for you in a few days, I'm still trying to digest results I'm seeing from the titanium cathode.

Jon Rosenstiel

User avatar
Richard Hull
Moderator
Posts: 12204
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Cube fusor build

Post by Richard Hull » Mon Oct 28, 2019 8:57 pm

One has to be also concerned about the anisotropy that you noticed in the previous post related to the cylinder electrode which seems more beam on target related. The BC-720 neutron detector is about the smallest rather directional neutron detector one might employ to look for signs of anisotropy. Unfortunately you have to have a rather rich source of neutrons to rely on its typical 0.5% efficiency.

My very first fusion was detected back in 1999 using a BC-720 I paid a small fortune for from Bicron. I might have to pull it out of storage in future for use with big neutron numbers.

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.

Jon Rosenstiel
Posts: 1391
Joined: Thu Jun 28, 2001 5:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Cube fusor build

Post by Jon Rosenstiel » Mon Oct 28, 2019 11:13 pm

Richard,

Joe Gayo found an interesting paper on isotropy / anisotropy.

Link to Joe's post...
https://www.fusor.net/board/viewtopic.p ... 9&start=30

Link to the paper... (See pages 18 & 19)
https://ir.library.dc-uoit.ca/bitstream ... Leslie.pdf

Jon Rosenstiel

User avatar
Richard Hull
Moderator
Posts: 12204
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Cube fusor build

Post by Richard Hull » Tue Oct 29, 2019 4:44 am

I can now see how your system as made here can be more neutron directed that our classic fusor being a loose form of beam on target due to the low energies we tend to use. This being the case, why aren't the more focused directional neutron number you get far above those of the spherical more isotropic system?

Oops I re-read some of the old posts regarding the poor numbers and understand you will be running and reporting on loading with the new titanium cylinder, which you have not reported on yet. Sorry, you advised me to wait a while as you will be doing this next. Memory, ain't what it used to be.

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.

User avatar
Jim Kovalchick
Posts: 438
Joined: Thu Apr 14, 2011 12:00 am
Real name:

Re: Cube fusor build

Post by Jim Kovalchick » Tue Oct 29, 2019 9:27 pm

Jon,
You are making good efforts trying to understand the neutron emission spatial characterization.
I'm far from expert, but I sense that emissions in your latest device are too complex to understand with conventional detectors. CR-39 plastic placed at various orientations might shed some light.

I think Monte Carlo in the right hands might be the answer.

Getting down to it, I'm not sure I would care if I were you. For me, it would be more about does this configuration let me get an activation sample in a higher flux because that is what I want to do with my neutrons. Even if fusion rates are smaller, the geometry may let you get samples closer to the point of neutron birth. Maybe you can compare activation to your original fusor. Another side benefit could be that new one uses less D. Who knows, but those questions' answers maybe more important than total numbers.

Post Reply