She’s still a runner! (1.2E+07 n/s)

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Jon Rosenstiel
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She’s still a runner! (1.2E+07 n/s)

Post by Jon Rosenstiel » Mon Jan 05, 2009 10:33 pm

It’s been a year-and-a-half since I last put the “pedal to the metal”… http://www.fusor.net/board/viewtopic.ph ... 732#p12242 Figured it was about time to find out if she “still had it”. I was tremendously relieved to see that my fusor has completely recovered from the performance killing cathode tests (and two subsequent complete rebuilds) done at the beginning of ‘08.
http://www.fusor.net/board/viewtopic.ph ... 796#p12306
http://www.fusor.net/board/viewtopic.ph ... 799#p12309

Input voltage: 80 kV
Input current: 21 mA
Input power: 1680 W
Pressure: 9.3 mTorr
Run time: 30 seconds
TIER: 1.2E+07 n/s

Jon Rosenstiel
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Wilfried Heil
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Wilfried Heil » Mon Jan 05, 2009 10:39 pm

Jon - fantastic!
The 80kV is rectified AC? Is this the voltage at it's peak?

Jon Rosenstiel
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Jon Rosenstiel » Mon Jan 05, 2009 10:53 pm

Hi Wilfried,

I'm running a high-frequency driven (40 kHz), 8-stage full-wave multiplier, so it should be fairly pure DC. The 80 kV value is taken from my home-built metering system, so one should probably figure on a plus /minus 10%.

Jon R

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Carl Willis
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Carl Willis » Mon Jan 05, 2009 10:59 pm

Wicked stats, Jon. Really...what more is there to say?

-Carl
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Chris Bradley
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Chris Bradley » Mon Jan 05, 2009 11:06 pm

You'd need to be running some big caps to hold up a smooth DC at that current. Maybe the 40kHz drive is actually providing a ripple at the top of the DC that is promoting this long sought-after resonant bunching? The theoretical equations are easy to run through to determine the ripple - what are the capacitors you're running, and your est. driving voltage?

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Carl Willis
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Carl Willis » Tue Jan 06, 2009 12:20 am

Hi Chris,

I think Jon and I use the exact same stack, and incidentally, Tim Koeth just got one and posted a schematic here: http://www.physics.rutgers.edu/~koeth/t ... ematic.pdf Bottom line: it has eight full-wave C-W stages--the charging caps are 10 nF, three per stage (two hot legs and the return leg). In addition are two smoothing columns, each of which is also 10 nF per stage. The final stage has a series inductor of unknown value for ripple reduction. The stack was designed for input at 18 kHz / 10 kV peak, and output of 82.5 kVDC / 50 mA according to company literature.

An SLR drive circuit such as Jon and I use is driven by pulses that are at twice the frequency of the output sine wave from the HV transformer. I suspect that Jon is running the drive circuit at 40 kHz, but that the output of the transformer is ideally (and probably mostly) 20 kHz power.

Ripple in the output will depend on the load capacitance, the unknown inductance in the top stage, and the harmonic content of the HV RF. It might be difficult to calculate with useful accuracy. I got a 150 kV Ross compensated divider for this kind of job a few months ago, in light of the fact that as Jon discovered, peak voltage is very important; but have not done anything with it yet.

-Carl
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Jon Rosenstiel » Tue Jan 06, 2009 1:16 am

Chris,

Carl is correct; he and I have the exact same stack. Here’s a few pix of mine.
viewtopic.php?f=11&t=4594#p27432
viewtopic.php?f=6&t=2727#p12237

To clarify my “fairly smooth DC” statement….I was comparing it to my previous HV supply, a 60 Hz unfiltered x-ray power supply.

Carl,

Thanks for chiming in, and thanks for the link to the schematic. And you're correct about the drive frequency...my bad.

Jon R

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Richard Hull
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Richard Hull » Tue Jan 06, 2009 3:22 pm

Carl, who is avowed to do battle for the numbers with Jon, has had the bar raised by this record run!

Great work Jon! The 2mr/hr of neutrons is rather distressing but the numbers you are getting forces that result. I am sure you are shielded for this level.

Keep up the great work.......

Carl, the ball is bouncing in your court....

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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Carl Willis
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Carl Willis » Tue Jan 06, 2009 10:07 pm

Hi Richard,

I hear you. My effort to win at the numbers is a long-term commitment, and I'm trying to enjoy the journey as much as the inevitable result of rightfully taking back my belt! (Mmm, that's enough chest-thumpery for one day.) Truthfully, I'm honored to be runner-up to such a fine effort as Jon's.

-Carl
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Chris Bradley
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Re: She’s still a runner! (1.2E+07 n/s)

Post by Chris Bradley » Tue Jan 06, 2009 11:00 pm

That makes it clearer. So, do you think if there is an overlay ripple that it could cause improved figures? These are outstanding (good work Jon!) yet just voltage and current alone doesn't appear to fully account for the gain on past performance. Any other 'tweaks' going on there worth considering further exploration/development?

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