Interesting operating session - Fusor IV

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Richard Hull
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Interesting operating session - Fusor IV

Post by Richard Hull » Mon Nov 14, 2005 2:52 pm

Yesterday, I tried a new process in fusor operation. I post the final conditions where I operated for about 7 minutes after a 2.4 hour startup procedure from dead cold.

1. Applied accelerator voltage 21.5kv
2. Measured stable fusor currrent 40ma
3. Deuterium gas pressure 18 microns (1.8 X 10e-2 torr)
4. Measured and corrected neutron count on large area He3 detector - 1580 counts per minute.

I managed to activate silver foil to about double background during this period. It was sandwiched between two 2" blocks of UHMW polyethylene and placed in virtual contact with the fusor shell. (1/4" separation)

Discussion:

I was rather stunned, at first, for this was about the level of operation we pushed fusor IV to back at the HEAS conference where we worked up near 30kv. It seems even at the lower cross section found at 21.5KV, higher current operation will drag the resultant fusion of the fusor up to a decent level.

The grid became very hot, naturally, but no damage was seen to be done. I could smell the hot stainless steel shell four feet away. Even the aluminum vertical staunchions were too hot to touch at shut down. The entire upper insulator metal portion was quite radioactive (5 times background) due to radon daughter collection over the long start up and run period. This has been noted before. No neutron activation of any components near the system was recorded. This result was expected, of course.

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
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Re: Interesting operating session - Fusor IV

Post by Jon Rosenstiel » Mon Nov 14, 2005 4:24 pm

I'll bet she got hot, that's a bunch of power. You've got yourself a nice 860 Watt space heater there!

Silver activation is a real kick. It really helps to move fast in order to catch the 25 second Ag-110 activation product. Really makes the Geiger counter (and the heart) sing.

Thanks for the report.

Jon Rosenstiel

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Richard Hull
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Re: Interesting operating session - Fusor IV

Post by Richard Hull » Mon Nov 14, 2005 7:29 pm

Yes, I made it so I could get that fast product. Maybe not the first half life, but certainly all of the second one and naturally, you get the 2.25 min silver 108 as well, provided you had a decent neutron flux for over 10 minutes.

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.

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Re: Interesting operating session - Fusor IV

Post by Starfire » Mon Nov 14, 2005 9:49 pm

Nice run Richard - I am very interested to know the lowest voltage at say, 20 micron, at which you can run sucessfully.

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Re: Interesting operating session - Fusor IV

Post by Richard Hull » Tue Nov 15, 2005 4:13 pm

At the high currents and near 20 microns, I was getting obvious, non-statistically dependent counts at 15 kv! I will admit that this is solely due to the large He3 counter and not the fusor being run in some amazing mode.

I can't stress the value of the use of a large He3 neutron detector tube placed in a large moderator connected to a well done electronic setup and located less than 3" from a supposed neutron producing device under test. It responds rapidly and in an unambiguous manner to very low neutron numbers.

Rem balls and the venerable PNC-1 counters are nice, but they are pitiable responders to light fluxes of neutrons and must be necessarily statisically monitored to fish neutron counts out of their own limited responses. They are truly health physics devices for use around active megawatt reactors and accelerator facilities where neutron fluxes are real and dangerous.

The problem is a large He3 tube and its associated electronics are a bit expensive, normally, and even if a deal is found, they require some amount of electronic skills to implement from scratch. (preferably a NIM setup with appropriate modules)

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.

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Re: Interesting operating session - Fusor IV

Post by 3l » Sat Nov 26, 2005 8:30 pm

Hi Guys:

The best voltage for pulsed fusors is 10 kv for high neutron yield.
Raise the voltage to 15 kv the neutron count will fall at the same amperage!
Dr Miley verified the effect on a log chart using various amperages at 15kv and 10 kv.
The theory is that the lower the voltage the longer the deuteron lingers in the grid before escaping.

Happy Fusoring!
Larry Leins
Fusor Tech

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Re: Interesting operating session - Fusor IV

Post by AnGuy » Sun Nov 27, 2005 7:43 pm

>Dr Miley verified the effect on a log chart using various amperages at 15kv and 10 kv.
The theory is that the lower the voltage the longer the deuteron lingers in the grid before escaping.

I haven't read Dr Miley's information, but could this also be dependant on the radius of the vacuum chamber used? Perhaps higher yields at higher pulsed voltages would occur with a larger volume of vacuum space. I wonder if the reason for lower yields at higher voltages is caused by arcing or some other event that drains the pulse charge. Perhaps the lower voltage prevents this from occuring which simple causes more ions to be accelerated. If this is the case then Dr Miley might have found the optiminal voltage for his device, not necessarily for pulsed fusion.

Where did you get this information about Dr. Miley's research? I would be interested in reading it. I would like to know if he ran his tests with multiple devices with different sized chambers.

BTW: Are you back into fusion experimention, or are you still working on your new house?

Thanks

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Re: Interesting operating session - Fusor IV

Post by MARK-HARRISS » Mon Nov 28, 2005 12:41 pm

Hi Larry, How did the pulse widths compare?

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