Farnsworth biography - Fusor development

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jlumartinez
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Farnsworth biography - Fusor development

Postby jlumartinez » Fri Nov 06, 2009 1:19 am

This is a link to a chapter from the book "Lost Science" (by G. Vassilatos) about Farnsworth´s life and the historical development of the fusor:

http://www.hbci.com/~wenonah/history/fusor.htm

Another link to fusor history: http://www.farnovision.com/chronicles/f ... latos.html

CharlesKramer
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Re: Farnsworth biography - Fusor development

Postby CharlesKramer » Sun Mar 09, 2014 7:01 pm

jlumartinez wrote:This is a link to a chapter from the book "Lost Science" (by G. Vassilatos) about Farnsworth´s life and the historical development of the fusor:
http://www.hbci.com/~wenonah/history/fusor.htm
Another link to fusor history: http://www.farnovision.com/chronicles/f ... latos.html

Great history of Philo T's place in fusion (and Polywell) history!

And it is consistent, at least, with the idea he was really trying to achieve practical fusion in his lifetime -- not just doing an interesting experiment.

From the article:
With deuterium gas in the Mark II Model 2 Fusor a count exceeding 50 M­neutrons cc/sec was recorded at 80 Kv. and 30 rnA. input. This device produced 1.3 G-neutrons/sec. in a sustained reaction for more than one minute. These reactions were stable, completely under the operator's control, and could be repeated.
The Mark III Fusor produced startling high records in quick succession. By the start of 196.5 the team was routinely measuring 15.5 G-neutrons/sec. at 150 Kv and 70 mA.

Does anyone know how Philo T's successors numbers compare?

-- Hirsch-Meeks

-- Bussard's Polywell

-- Current Polywell

A steady line of improvement would not be proof Polywell (or *its* successors) will ultimately succeed. Still... would be interesting to see the time line -- where everyone fits, and where and when if progress continues success might be expected.
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KitemanSA
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Re: Farnsworth biography - Fusor development

Postby KitemanSA » Thu Mar 13, 2014 3:52 am

jlumartinez wrote:This is a link to a chapter from the book "Lost Science" (by G. Vassilatos) about Farnsworth´s life and the historical development of the fusor:

http://www.hbci.com/~wenonah/history/fusor.htm

Another link to fusor history: http://www.farnovision.com/chronicles/f ... latos.html
Obviously all that "lost science" is in Warehouse 13.

CharlesKramer
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Re: Farnsworth biography - Fusor development

Postby CharlesKramer » Sun Mar 16, 2014 8:54 pm

From the article:
The Mark III Fusor produced startling high records in quick succession. By the start of 196.5 the team was routinely measuring 15.5 G-neutrons/sec. at 150 Kv and 70 mA.
Does anyone know how Philo T's successors numbers compare?
-- Hirsch-Meeks
-- Bussard's Polywell
-- Current Polywell
A steady line of improvement would not be proof Polywell (or *its* successors) will ultimately succeed. Still... would be interesting to see the time line -- where everyone fits, and where and when if progress continues success might be expected

I find interesting this information appears not to exist. I would expect any bid for money for Polywell would tout a history of continual (even geometric) improvement.

CBK
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Blog: http://www.provideocoalition.com/ckramer

D Tibbets
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Re: Farnsworth biography - Fusor development

Postby D Tibbets » Wed Mar 19, 2014 12:07 am

Hirsch was a research fellow in Farnsworths lab in the late 60's. I'm not sure whar his machine was called, but it recorded neutron outputs of ~ a billion per second. Perhaps higher as reported above. This was at ~ 100 KeV or greater, and I think with D-D fuel. I'm uncertain if D-T was used, but if so the fusion output may have been ~ 10-100 times higher at more modest voltages (D-T fusion cross section peak is at ~ 50 KeV.

Bussard mentioned this record in the context of WB 6. His claims of ~ 500 million neutrons per second matched the "record" (within an order of magnitude), and importantly did it at energies of 10 KeV, where the D-D fusion cross section is ~ 100 times less.

This is nice but not very useful. What makes the Polywell remarkable (if claims are true) is how much it scales up with increased magnetic field strengths. Keep in mind that a few billion neutrons per second only represents a fusion output of a few milliwatts.

Dan Tibbets
To error is human... and I'm very human.

CharlesKramer
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Re: Farnsworth biography - Fusor development

Postby CharlesKramer » Tue Mar 25, 2014 2:57 pm

D Tibbets wrote:This is nice but not very useful. What makes the Polywell remarkable (if claims are true) is how much it scales up with increased magnetic field strengths. Keep in mind that a few billion neutrons per second only represents a fusion output of a few milliwatts.

Very interestin', thanks!

Forgive me if this is a stupid question -- and I do understand Polywell and ITER/Tokamak are very different approaches to fusion.

But is scale also a reason why there is hope for ITER? Presumably it won't be different in kind than JET, JT-60 and other Tokamaks, but mostly just bigger.

CBK
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hanelyp
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Re: Farnsworth biography - Fusor development

Postby hanelyp » Tue Mar 25, 2014 9:04 pm

Power output for magnetic confinement devices scales as B^4R^3 pretty universally. Presuming losses scale slower than R^3, you can get better fusion gain by going bigger. The problem they've run into building bigger tokomaks is new unanticipated turbulence loss modes, related to the magnetic field curvature and profile. The polywell is hoped to be immune to such instability modes with the magnetic field getting uniformly stronger as the plasma pushed it away from the center.
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CharlesKramer
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Re: Farnsworth biography - Fusor development

Postby CharlesKramer » Fri Mar 28, 2014 11:51 am

hanelyp wrote:Power output for magnetic confinement devices scales as B^4R^3 pretty universally. Presuming losses scale slower than R^3, you can get better fusion gain by going bigger. The problem they've run into building bigger tokomaks is new unanticipated turbulence loss modes, related to the magnetic field curvature and profile. The polywell is hoped to be immune to such instability modes with the magnetic field getting uniformly stronger as the plasma pushed it away from the center.

Interesting, thanks.

I don't doubt what you say. Presumably ITER (a scaled up Tokamak) and current Polywell work reflect the hope bigger will be better.

But this area is confusing. I just read about the "mini-Tokamak" line of fusion hopes in which Bussard (yes, of Polywell fame) urged the opposite: small is better: http://www.askmar.com/Robert%20Bussard/ ... erview.pdf

"As the most vocal and visible advocate of the small-is-
better school of fusion, a former rocket engineer recalls
the frustrations in trying to persuade Uncle Sam not to
think big."

The idea has apparently been revived by IGNITOR http://www.iter.org/newsline/131/169 and http://www2.lns.mit.edu/ignitorproject/ ... /Home.html
================================
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Blog: http://www.provideocoalition.com/ckramer

CharlesKramer
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Re: Farnsworth biography - Fusor development

Postby CharlesKramer » Fri Mar 28, 2014 11:54 am

hanelyp wrote:Power output for magnetic confinement devices scales as B^4R^3 pretty universally. Presuming losses scale slower than R^3, you can get better fusion gain by going bigger. The problem they've run into building bigger tokomaks is new unanticipated turbulence loss modes, related to the magnetic field curvature and profile. The polywell is hoped to be immune to such instability modes with the magnetic field getting uniformly stronger as the plasma pushed it away from the center.

Interesting, thanks.

I don't doubt what you say. Presumably ITER (a scaled up Tokamak) and current Polywell work reflect the hope bigger will be better.

But this area is confusing. I just read about the "mini-Tokamak" line of fusion hopes in which Bussard (yes, of Polywell fame) urged the opposite: small is better: http://www.askmar.com/Robert%20Bussard/ ... erview.pdf

"As the most vocal and visible advocate of the small-is-
better school of fusion, a former rocket engineer recalls
the frustrations in trying to persuade Uncle Sam not to
think big."

The idea has apparently been revived by IGNITOR http://www.iter.org/newsline/131/169 and http://www2.lns.mit.edu/ignitorproject/ ... /Home.html
================================
CBK
Blog: http://www.provideocoalition.com/ckramer

hanelyp
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Re: Farnsworth biography - Fusor development

Postby hanelyp » Fri Mar 28, 2014 3:46 pm

The line "The high magnetic field in the device (up to 13 Tesla on the plasma axis, more than twice that of ITER) ..." appears relevant to IGNITOR scale. It looks like they're trying to push the B^4 factor.
The daylight is uncomfortably bright for eyes so long in the dark.


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