The Farnsworth Multipactor

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Re: The Farnsworth Multipactor

Post by Brett »

Oh, I don't doubt that there would be *some* focusing effect, just the extent of it.

The more I think about fusion, the less I think fusors have real potential. We have two demonstrated ways of getting a net power output from fusion: Stars, and hydrogen bombs. Both involve plasmas which are much denser than normal matter. The fusor, or magnetic containment fusion, is so far from those conditions it's not funny.

So I'm trying to think up a way of producing that kind of high density plasma on a scale comparable to a fusor. Has anybody done anything with electrostatically accelerating D2 pellets, and colliding them? I suspect I could put enough kinetic energy into a *small* pellet to achieve fusion temperatures on collision, given an accelerator which would fit in a garage.
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Re: The Farnsworth Multipactor

Post by Dustinit »

Sounds like you need end to end evacuated rail guns. The mind boggles at the energies required for a single shot and certain destruction of the barrels in a single shot.

I think what wilfried says does make some sense although my own attempts deviate from this line somewhat. Instead of an rf between the shell halves which would slosh electrons and ions from one side to the other, I imagine the RF imposed on the DC of the shells with respect to the centre electrode. (or the other way around)
In this case the electrons and ions alternate their focus on the centre electrode. If the frequency is set so that the ions reverse direction before they hit the shell, This would mean thet the electrons (having lower mass) would hit the shells hard emitting secondary electrons (up to 7 for every electron collision) just in time to be accelerated into the centre on the voltage reversal.
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Re: The Farnsworth Multipactor

Post by Brett »

You'd use electrostatic accelerators: The smaller you make the pellet, the higher the charge to mass ratio you can achieve, and thus the higher the accelleration. You'd probably have to fuel it with lithium deuteride dust, D2 dust would be hard to make.

I actually did some calculations on that years ago, in relation to using soot for reaction mass in an 'ion' drive. To achieve fusion energies with pellets that were bigger than atomic clusters you'd need some pretty high voltages, but I think it would be doable.
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Re: The Farnsworth Multipactor

Post by Wilfried Heil »

>How can this reach fusion temperatures then, if this plasma is not confined away from all parts of the reaction vessel?
The plasma is confined by the electrostatic field of the virtual cathode, i.e. the potential well in the center of the device. Same procedure as in an IEC fusor with a real cathode.

"Cold cathode electron discharge tube" US patent #2263032 from 1936, for a multipacting oscillator. This is Farnsworth's version of the "Dynatron" negative differential resistance amplifier. While fully functional, such amplifiers were soon abandoned when fast and sufficiently high powered vacuum tubes became available.

>http://patft.uspto.gov/netacgi/nph-Pars ... er=2263032

Although originally not intended for fusion, it contains all the features that one would need.
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Re: The Farnsworth Multipactor

Post by Dustinit »

I think the RF makes things much more complex than it needs to be.
If it is just being used to multipact and create electrons then you could use a filament and have steady state operation. I guess apart from filament current this should be less of a load on the HV supply as electrons have a chance to recirculate as opposed to all of them being lost to the shell.

I suppose you could run without the filament and simply reverse the polarity in an existing fusor setup to get the same effect.

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Re: The Farnsworth Multipactor

Post by Paul_Schatzkin »

The regulars will be surprised to see this 16-year-old thread rise to the top of the Active Topics. Ah, the hidden value in a 25 year old archive/database!

I'm working on my presentation for the Cosmic Summit in June. I'm still not sure what I'm going to offer (or, at times, even 'if').

This morning, while conjuring up a timeline that led to the fusor, my wanderings returned me to the topic of the Multipactor tube. When I Googled the term, this thread was was number three in the search results so I dug in.

What perplexes me at the moment is the disparity between Richard's account of the Pontiac Street era and what Pem Farnsworth reports in Distant Vision. Even more perplexing is the disparity I now see in Richard's own accounts (as quoted here).

In the post that begins this thread, Wilfried Heil (where is he now?) quotes Richard, or perhaps I should say 'paraphrases' because I search of the site failed to produce the exact same terminology:

viewtopic.php?p=42535#p42535
Wilfried Heil wrote: Tue Dec 09, 2008 4:40 pm I quote Richard here:
>Having spoken with all the techs and engineers in person on the Farnsworth team for many hours of interviews in person in Fort Wayne and over any number of phone interviews over the years, Farnsworth refused to accept that his electron bombardment idea was not all that valid. They... told stories of the tedium between 1960 and 1964 of no results, numerous modifications... with no neutrons in evidence.
On page 289 of Distant Vision Pem Farnsworth writes that in October, 1960, after adequate shielding and crude instrumentation was obtained, "the neutron account increased as the voltage increased."

That seems a direct contradiction to the "no neutrons" quoted above, as well as Richard's post to the "Attic" in 2022:

viewtopic.php?p=97498#p97498
Richard Hull wrote: Fri Dec 23, 2022 1:44 am Finally no glass bell jar fusor, according the Gene Meeks, ever hit more than 10e3 - 10e4 D-D fusion neutron output! This was from 1959 thru early 1963. Hirsch noted to me that when he came for that first summer in 1963 "Richard, these guys were still working with bell jar systems!"
...and while yeah, we're talking bell jar fusors, and 10e3-4 may not be much, it's still more than 'no neutrons.'

So we have a post from Richard in 2022 that contradicts a post from 2008, though I gather both are based on accounts from... 1999?

So what are we to believe, there were or were not neutrons prior to Hirsch's arrival in 63-64?

If nothing else, adding a new post to this thread will put it at the top of the fora, and give newer users and visitors a look at some of the older discussion re: the origins and earliest iterations of the fusor.

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Re: The Farnsworth Multipactor

Post by Richard Hull »

From 1960- late1962 the team had no neutron counter! If what they needed didn't exist at Pontiac street, they did without. Gene cobbled together their first HV supplies from the old stores of the discontinued TV manufacture which ended in 1958! His second supply built in December 1960 could just do 34kv.

They had no money until the 1962 budget. It was then that they obtained a really fine 50kv universal voltronics power supply and in September a brand new Eberline PNC-1 neutron counter.

According to Hirsch, when he arrived in summer of 1963, they were still piddling around with all glass bell jar fusors and were getting very low neutron counts using deuterium gas, only.

Meeks, Bain and Haak, (arrived 1961) claimed that Farnsworth relied on two surplus military Geiger counters to claim fusion until they got a neutron counter which barely ticked when first used in early 1963. Bain and Meeks said that they always felt 1960-1963 that the roar of the GM counters were due to x-rays, which we all here know, that near a fusor, a GM counter will go nuts.

Thus, whether they produced any neutrons or not 1960-63 will never be known as they could not count them. The roaring GM counter early on produced grave concerns by the higher ups overseeing the program.

The Farnsworth effort was effectively a clown show 1960-62. No one had any knowledge related to neutron radiation detection! Not one human being on the team or at Pontiac street's high offices had any experience with radiation or its measurement!! I have reported that both Bain and Meeks had to more or less self-educate themselves in the area of radiation as they felt Farnsworth might be deceiving himself in his record keeping and reporting.

Regardless, the glowing reports from Farnsworth to his overloads forced them to cut loose with the first real money for the 1962 budget which saw the first professional HV supply arrive and a much needed neutron counter. Finally, their improved glass bell jars could be proven to be doing fusion.

Again, What did Pem know of radiation and neutron counting? Zip! She relied on her beloved husband to tell her what was going on.

Thank God I went to the worker bees and got the straight dope before they started dying. I was the only one that ever interviewed 100% of all these technical and engineering, fusor pioneers. They respected that I had done D-D fusion, that I had a working and useful knowledge of radiation physics, (neutron detection physics specifically), vacuum system assembly, and that I had a professional level of electronic background and fully understood what they went through. Many have interviewed only a few of them for a quick rinse in the basic history in the past. No one with the technical, electronic and nuclear chops ever interviewed them related to the reality of working, day-to-day technical details related to the fusion effort in their lab. They told me things that they admitted they never bothered to tell others. They all told me that they would not openly besmirch the reputation of Farnsworth. They all respected him as a man. However they all, to the man, felt he was unprepared for the work and 4 admitted that they, too, as it turned out, were also unprepared. They were thrown into the caldron of having to perform in an area for which they had no real background or useful knowledge, for a time.

All on the team, in the end, admitted that the work really took off with the arrival of Hirsch, metal fusors and deuterium-tritium fueling. Oh, in 1964 they purchased a giant rack controlled Universal Voltronics 150kv supply for the pit fusor, later shared with the cave fusor. Money flowed rapidly from 64-67. Farnworth, as a working, functioning team member, ended for the most part in 1961 with his virtual total displacement taking place with the arrival of Hirsch.

1960-1962 no neutron counter (open, yet unrealized self-deception)
1961-1962 Bain and Meeks self-educate themselves in rudimentary radiation physics over doubts about Farnsworth's claims
1961 The arrival of Haak makes for three main working team members plus one technician always there (3 total came and went)
1960-1963 All glass fusors
1962-1967 Money starts to flow, ever more increasing until the end.
1963-1964 Accurate, honest neutron counting and detection showing weak but real fusion in the last glass fusors fueled by deuterium, only.
1964-1967 end of glass fusors, all metal fusors. Real fusor work, D-T fueled fusors takes over and true scientific advancement.

Richard Hull
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Gene circa early 1962 sitting at one of the last glass fusors being run by his second and last decent hand built hv supply, nursing a deuterium fueled fusor.  No PNC-1 neutron counter in sight.  Photo from Bain collection turned over to Richard Hull
Gene circa early 1962 sitting at one of the last glass fusors being run by his second and last decent hand built hv supply, nursing a deuterium fueled fusor. No PNC-1 neutron counter in sight. Photo from Bain collection turned over to Richard Hull
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Re: The Farnsworth Multipactor

Post by Paul_Schatzkin »

Richard Hull wrote: Fri Apr 19, 2024 2:01 pm What did Pem know of radiation and neutron counting? Zip! She relied on her beloved husband to tell her what was going on.
Never mind what Pem knew...

Your own 2022 post said, and I repeat,
no glass bell jar fusor, according the Gene Meeks, ever hit more than 10e3 - 10e4 D-D fusion neutron output!
How, based on what you're saying here, did they even measure that much?

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Re: The Farnsworth Multipactor

Post by Richard Hull »

As noted from early 1963 through 1964, part of the last gasp of the glass bell jar work, The team had two things brand new due to funds of 1962......

They had a real working neutron counter. They had a nice new 50kv Universal Voltronics 50,000 volt power supply that let them go beyond the 1962 limit of 34,000 volts into their fusor.

Thus, they did real proven fusion for about a year and a half in glass bell jar fusors! Albeit at a rather low level. (Meeks statement to me) From this the best they ever did in glass fusors 1960-64 was what they measured in those last 18 months where they knew what they were getting....

They worked at low pressures in the 3 micron range when successful at the end with deuterium in glass. Fusors cannot ever do fusion in glass at our level where pressures are 8-20 or more microns due to simple gas plasma dynamics. More D2 means more current, more current means more heat and glass implodes via local beam heating. That is why they, and we, do more fusion in all metal systems. This is why we tell newbies to never attempt any fusion in glass containment vessels! One thing that did come from all the clown circus days. 1960-62... They learned to vacuum out the glass well and just let a tiny bit of deuterium in to avoid implosion at high voltage and resultant currents. 34,000 volts from Gene's best and final homebrew HV supply was not a lot of voltage to do decent fusion in glass. It was enough to implode a glass system at high currents with higher Deuterium gas pressures where fusion can really "step out" to higher levels.

All of the above knowledge comes from self-directed learning, but far more so due to the "hands on imperative"... the "doing" which allows you to be one with the science and physics...to own it, internally..
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The last and best technican for the team at the pit fusor rack group needed to control the vacuum, ion gun and the oil drummed 150kv Universal Voltronics power supply.  According to Gean Meeks the supplys: 1960 - 18kv homebrew, late 1960-62 - 34kv homebrew, 1962-64 50 kv universal voltronics, 1964 to 67 - 150kv Universal Voltronics.
The last and best technican for the team at the pit fusor rack group needed to control the vacuum, ion gun and the oil drummed 150kv Universal Voltronics power supply. According to Gean Meeks the supplys: 1960 - 18kv homebrew, late 1960-62 - 34kv homebrew, 1962-64 50 kv universal voltronics, 1964 to 67 - 150kv Universal Voltronics.
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Re: The Farnsworth Multipactor

Post by Richard Hull »

As a small real world, doing and learning experience I post the following.

In mid 1998 I had fusor II, an advanced demo working in a bell jar. After learning much from it, I admitted Deuterium to a pressure of about 8 microns and nursed the system up to 24,000 volts at 10ma. I had a beautiful pink star mode. We all know this is a sign of good operation and fusion.

Suddenly, a red hot flake of glass about the size of a house fly fell into the base. I immediately shut the fusor II down and never tried this ever again. I just knew I had done fusion, but never claimed it as my early neutron counter was only 1% efficient and I did not have it hooked to a counter timer then.

I immediately went to work on building fusor III a stainless steel vessel and also picked up my PNC-1 off e-bay (same as used by ITT fusor team). I succeeded in doing recorded fusion in early 1999.

Thus, the continuing warning to newbies to never attempt fusion in a glass bell jar or any glass vessel. This includes over driving even a demo fusor in a bell jar!!!

Richard Hull
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Re: The Farnsworth Multipactor

Post by Paul_Schatzkin »

Richard,

I know a lot of this has been hashed out before and elsewhere, but since we've got this thread going here now...

I've been looking through these posts again:

viewtopic.php?p=97500#p97500
Richard Hull wrote: Fri Dec 23, 2022 12:11 pmHowever, he was warned about not operating it without permission once his huge numbers were reported. Gene felt this was the machine that was close. I think he was just excited due to his numbers. It was not "close", it was just the sum of their knowledge packed into one last effort by the "best pair of hands" on site.
One thing I find curious is the warning 'not to operate.'

I've been reading/recording TBWIT for the audiobook version, and have just gone through again the chapters on fusion, and was reminded that – whatever else you want to say about Farnsworth's 'delusions' during this period – he had insisted from the start that the fusor needed to be operated a very high energy levels and wanted a facility that could safely accommodate those levels of in/output.
TBWIT Chapter 19 wrote: The entire operation occupied one relatively small room. To shield the workers, the fusor itself was eventually placed on a hydraulically operated elevator so that it could be lowered into a fourteen-foot hole that was dug through the floor of the basement. Farnsworth had wanted to operate his fusor in an entirely separate location; ITT put it in a pit.
So it's not surprising that when a configuration like the one Gene called "Mark II Prime" reached unprecedented neutron counts, the authorities at ITT would tell him "you better stop now."

I've attached the photo you posted of the machine in question. The caption reads "...claims of 10^12 were made by Gene...." Did you ever see any documentation of those results, or is that just Gene's verbal testimony?

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Constructed by Gene Meeks in late 1966, this would be the last fusor built and run in 1967 as the ITT effort was funded through to FY 1968. By mid-1967 ITT announced it would not fund the effort next year and the team was not doing much beyond Hirsch working on the final published report. The AEC had just refused to get involved. It was a dead time from summer 1967 to the end in late spring 1968.
Constructed by Gene Meeks in late 1966, this would be the last fusor built and run in 1967 as the ITT effort was funded through to FY 1968. By mid-1967 ITT announced it would not fund the effort next year and the team was not doing much beyond Hirsch working on the final published report. The AEC had just refused to get involved. It was a dead time from summer 1967 to the end in late spring 1968.
FusorITT3 Mark II prime.jpg (47.6 KiB) Viewed 807 times
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Re: The Farnsworth Multipactor

Post by Richard Hull »

Regarding Mark II prime: No! I have seen but little real documentation from the lab work during the entire effort. Files were kept at ITT, I am sure. What happened to them is anyone's guess. As to Gene's claims for the Mark II Prime, I never saw any documentation.

Steve Blaising and Fred Haak both told me that George Bain and Bob Hirsch were very serious about Gene not running it due to its high output. It was right below Farnsworth's office. As Farnsworth was long gone in 1967, I would imagine the office was occupied by someone else. I think the fact that it was not in a pit and not in a neutron absorbing cave, gave the team leaders pause.

It is to be noted that the Mark II prime was a fully ion gunned system! (see photo above) Perhaps as good as or better than the cave fusor! I am sure its numbers were very impressive if not rather frightening in an unshielded environment.

This was late in the ITT effort. Gene told me that Bob was in and out preparing to leave for his promised AEC position and when George was either very busy or out at the same time, he would run it, in spite of the admonitions, chuckling to himself. Gene remained a lifelong imp, even when I knew him. He loved to poke the bear. This nature almost cost him his job early on in the fusor effort at ITT.

Do I think Gene reached 10e12? No! I do think it was a superior performer or he would not have been forbidden to run it once his numbers were shared with his superiors. Gene was a very quick study and save for the lack of a college background, I think during his 2 1/2 years with Hirsch, he became a master in all aspects of fusor construction, operation and data taking. In 1960, Like Bain, Gene was thrust into the effort ignorant of fusion and the technologies and physics involved, but by the time he joined Hirsch in the cave, his good pair of hands, soon blossomed into a good head for fusor fusion.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: The Farnsworth Multipactor

Post by David Kunkle »

If the Mark II Prime had reached 10e12, that's a million times more powerful than a good fusor like Richard's. It seems to me that would be highly useful as a neutron source if nothing else. And yet ITT decided it should all get tossed into the proverbial landfill?
If your experiment needs statistics, you ought to have done a better experiment.

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Re: The Farnsworth Multipactor

Post by Richard Hull »

I have noted that a lot of companies during the late 50s were sprouting fusion programs as there was hope of millions to the winner for fusion patents.

ITT was dragged into the fusion biz by Farnsworth, a new corporate president and the admiral. By the mid to late 60's many companies were backing out of their fusion quest as it seems no one, not even the government, was getting anywhere with fusion. ITT was no different, after boosting their fusion budget in 1962-1965. The failure of the team to produce a breakthrough and the report issued by Hirsch to ITT management offered little hope. If there was an icing on the ITT fusion effort doomsday cake, it was almost uniform negative comments by the requested opinions from leaders in the fusion and physics field. Almost universally they indicated there was little hope of the IECF method which Farnsworth put forth.

As I stated earlier, ITT immediately sought to turn over their effort, but not their patents, to the AEC thermonuclear research division and sent Hirsch with the dessert cart fusor to demo it before the governing body of the AEC. The AEC was impressed, but demurred. It was now late 1966. ITT said there would be no mid-1967 budget for the program. The AEC was very impressed with Hirsch and offered him a job. Hirsch left ITT in early 1967 and most Team members were seduced by Farnsworth to join him in Utah and work with his new company, Philo T. Farnsworth Associates.

ITT was out of the fusion biz and Haak and Blasing stayed on at ITT being reassigned to their old departments, later to retire with full pensions.

PTFA in Utah folded up within one year and all who put their trust in Farnsworth, disillusioned and out of work, scattered to the four winds.

Far more details on this has already been written above.

So yes, ITT put all the hardware they did not sell off and their dealings with fusion in a landfill.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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