Quaid Hawkins - Plasma and Progress

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Quaid Hawkins
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Re: Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

I have everything in the star grounding configuration. The fusor shell is connected directly to ground and the positive lead of the power supply is connected to ground through the 10 ohm resistor.

Quaid
"Get to the reactor!"
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Mark Rowley
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

Specific to the precip supplies, they don’t require a ballast resistor. They are not an X-ray transformer and they respond differently. I experimented with a ballast resistor last year and only found them to be an energy hog which chokes off the fusor (again, specific only to the precipitator). Even under stable conditions the resistor will heat up. So in effect, it will require you to push the precip even harder to get the higher voltages at the necessary amp requirements. You can experiment more with this but I found it better to discard their use. But for X-ray transformer systems, ballast resistors are a mandatory requirement.

Specific to a tiny cross fusor, a TMP is the pinnacle of overkill. Expect difficulty maintaining the required deuterium pressure without really cranking up the flow rate and throttling off the TMP to almost nil.

Your description of the voltage spiking when plasma extinguishes is normal with the precipitator. Try to avoid extinguishment when the voltage setting is to a point that It will max when it occurs. Being able to anticipate extinguishment only comes with operational experience. Just try to tread very lightly as you begin the learning process.

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Richard Hull
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Re: Quaid Hawkins - Plasma and Progress

Post by Richard Hull »

As a rule, the current you find workable will, though ohms law, dictate such a resistor's value. No ballast resistor need ever heat as the wattage should preclude this. A big current in my fusor is 20ma, that is it! Actual fusion currents hover around 15ma. E=IR....63X10e3 X .015 = 945 volts across my 150 watt resistor and stolen from my fusor..... P=I^2R... .015X.015X 63X10e3 = 14 watts of heat in a 150 watt resistor, virtually imperceptible.

If you choose to use a ballast resistor make sure, via ohms law, that it fits your system well. So many newer systems, smaller ones, need a good deal of current due to higher pressures. It is voltage that really drives fusion due to the huge slope of the capture cross section. Current and fuel pressure also figure it, but with lower voltages you are trapped. With only 45 kV on hand, I am trapped for the moment to what I can do. Anymore, 30kv is just starting to get underway, if research neutrons are your goal.

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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Mark Rowley
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

Richard, interestingly my current system rarely pulls over 3.5mA, even during the high output runs which enabled the Mg56 and Cu activations. It’s fairly close to the power demands of the smaller cross fusor with the only big difference being its solid operational stability. As you said though, voltage definitely drives the fusion. I’m peaking over 50kV at 3.5mA, 43mTorr deuterium when cranking out good numbers.

Regarding the precips, they have current limiting protection circuitry built into the system. It can be easily bypassed or modified (simple resistor value adjustment) for whatever ones end goal is.

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Re: Quaid Hawkins - Plasma and Progress

Post by Richard Hull »

Mark, you know those supplies and those with them should pay attention to your sage advice.

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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Quaid Hawkins
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Re: Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

Update as of June 8 / 2021

Mark was right, I blew out my power supply by operating it at >50mTorr. I ran a test on both my power supplies (similar to the ones finn hammer did a while back) and found that the one I was using was pushing out less than 0.1 mA, still up to 30kV though. Not completely broken, just wont work for the fusor anymore. The other power supply was able to put out a good 10mA at ~27kV. I wired that one up.

Precipitator Power Supply Test
PSU Test.jpg

Now for fun and to get a feel for the reactor I ran it with deuterium from the PEM cell, only about 10cc. Full system operation, yay! No neutrons, wasn't really even trying... mostly testing for noise, operational procedure, etc.

I am using the GS-Neutron with the GS-1100 pro about 3" from the chamber. With a discrimination threshold of 15. The cable I was using is particularly poor, long and un-insulated. But I got the following results running at around 27kV and over 8mA at the best of times.

Pulse height histogram
PulseHeightHistogram.PNG
PulseHeightHistogram.PNG (9.65 KiB) Viewed 3761 times
Count rate vs Time
count rate vs time.PNG

Steven Sesselmann once said that neutrons will be spotted above 50 arb.u. in the thread viewtopic.php?f=13&t=12032&hilit=gamma+spectacular. While I'm hopeful, I make absolutely no claims that there are neutrons but am hopeful that I can make a real neutron claim soon. The count rate vs time shows peaks from when either the pressure or voltage would drop from the needed levels (to produce noise or otherwise). The system is all in place with the right pressure, voltage, current combination, and now I need to work on the operation. Something I always heard was a challenging part.

Will keep updating as I work towards neutrons

Cheers,
Quaid
"Get to the reactor!"
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Richard Hull
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Re: Quaid Hawkins - Plasma and Progress

Post by Richard Hull »

In the scientific world all graphs have clearly printed units for both the x and y axis, printed on the axis. The graphs truly mean nothing to a trained observer trying to figure out what you wish to convey as data in the graphs.

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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Quaid Hawkins
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Re: Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

Yeah you're right, they don't mean scratch. The graphs are directly from pra, and the units in the histogram are in arb.u and would need to be calibrated against a reference for the x axis to mean anything anyways. I included them more or less for anyone familiar with the pra software.

Quaid
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Mark Rowley
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

Sorry to hear about the demise of the precip supply. But yeah, they don’t fare too well under the higher pressures, even a brief hiccup or burp could spell doom so extra caution must be exercised to keep the pressure in the acceptable range. After you’re done with the first step of getting neutrons, you may want to consider a scratch built “precip” design like the one here (or something similar).

viewtopic.php?t=13907

Based on how you wind the cores, you can have a supply that is considerably more robust and resilient to pressure inconsistencies.

Regarding PRA, I can see some issues with providing conclusive proof of neutron production. With that being said, PRA and Theremino are excellent for amateur gamma spec.

Since your fusor is almost a duplicate of the typical 2.75” cross fusor, the following numbers should provide more than enough neutrons for silver or indium activation:

30-34kV
25-30mTorr (microns) of continual deuterium flow
3mA drive current
Silver foil in sufficient moderator at 15cm or closer to core
3-5 minutes of exposure

Once done, immediately put the foil sample on a pancake probe and register the increased count rate. If you activate indium, in addition to the CPM rate, gamma spec will provide a host of irrefutable photopeaks.

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Richard Hull
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Re: Quaid Hawkins - Plasma and Progress

Post by Richard Hull »

Mark is correct. Nothing, and I mean nothing, puts you in the neutron club faster than neutron activation. However, if you have a flawless electronic neutron counting system and report openly and honestly related to neutron production, you will always be questioned and are subject to brutal cross examination by those in the know on the subject.

If you are not producing enough neutrons to activate, but enough to make the counter click above background to even the meanest intelligence, then do what "Clagwell" ,(Now known to be our own expert Mark Rowley), does in the video posted below.

That 3He tube looks Russian? Did he get his discrimination right? The voltage? Is he counting real neutrons? Hey, it's clicking away right? you bet it is but neutrons?? Here is where Clagwell proves 100% that he is counting neutrons.

With great care and precision we watch the video following his every move, he has positioned his big ugly black moderator right next to his fusor with his neutron detector tube in the moderator, which is a must have item surrounding the tube. He has also positioned at the same distance from his fusor, a glass flask. He removes the tube from the moderator where it is detecting what are supposedly now thermal neutrons and then drops it into the flask where the same number of neutrons are hitting the tube, but they are fast neutrons. The tube doesn't count anymore!! Why? Because it can only count thermal neutrons. He shows the meter isn't counting any more and for a couple of "in-and-outs", he shows beyond all shadow of doubt.....1. He has his neutron detector fine tuned and working at the proper voltage and 2. It will only count thermal neutrons.

Clagwell is proved to be a sharp cookie and has mastered neutron detection without ever activating anything, but even at a low count rate, demonstrates to all that he is doing fusion in his little fusor. It is that simple.

Please also note that he showed all of his instrumentation with believable values while the counter is clicking away. This proves we are viewing a working device within normal fusion parameters.

https://www.youtube.com/watch?v=MFOrEsPDrZw

If you ever show up claiming fusion via electronic neutron detection, but can't activate or afford a bubble dosimeter, this is how you do it and land in the neutron club.
I am so impressed by my own verbiage here, backing up the video, that I hope to make this into a FAQ, If I have not already done so.

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
User avatar
Mark Rowley
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Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

Lol…. In time I’ll come up with a better name. YouTube is the wild west compared to here so I’m not too keen on using my real name over there.

Regarding the video, it’s a prime example of learning how to operate or drive a fusor. When the video was made I had yet to learn the full capabilities of the power supply, the “sweet spot” for vacuum and deuterium flow, purging the lines, and how to slowly walk up the voltage (hence the low count rate). That ignorance, which we all possess at the beginning, is totally evident. It was only a couple weeks after that video where all the above was learned and activation capable numbers began to surface.

Quaid, if you’re interested, I can give you more detail on how to get those numbers up for activation if that’s the route you’d like to take.

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Re: Quaid Hawkins - Plasma and Progress

Post by Richard Hull »

You will just have to hang in there and listen to folks like the old time operators who have suffered the "learning curve" particular to their own fusors. Generalizations can indeed be made to assist in learning how to start, operate and control an amateur fusor. However, each fusor may and often does have individual quirks. (geometry, size, vacuum control issues, gas flow issues, sealing issues, etc.) First time control issues are as common as the sea sickness and each must get his "sea legs" over time.

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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