Quaid Hawkins - Plasma and Progress

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Quaid Hawkins
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Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

Update as of June 28/2020

Hey everyone, thought I'd show off some of my progress and a few plasma pictures.

Chamber and Vacuum
The chamber is the common 6-way 2.75" conflat cross.
My vacuum system I have an Edwards E2M2 backing an ext75dx turbo pump, and measurements made with a Hastings thermocouple gauge. After lots of cleaning I was able to pull down to 20 micron with just the roughing pump, and will hook up the turbo in the next week or so.

Power Supply
Right now I'm using a 5kv NST for demo while I work on the vacuum portions. I occasionally hook up the 30kV precipitator power supply but haven't been able to get more than 4kv out of it when running it with the fusor, but with test loads it's fine.

Neutron Detection
I'm using a CHM-12 proportional tube (from the GS-neutron) and have gotten expected background counts.

Deuterium
I do not have a deuterium system yet, but I'm either going to go with the PEM cell syringe method or try and work with my university and get a lecture bottle (but that's proving a bit difficult right now haha).

I'm a way off from the neutron producing fusor, but I hope that if I've made it this far a should be able to go the rest of the way. After I hook up the turbo I'll work more intensely on the power supply.

Cheers,
Quaid

plasma75micron.jpg
Plasma at 3.8kV with pressure of ~50 micron.


chamber and plasma.jpg
Conflat chamber - plasma looks much more blue than it does in person


Helium.jpg
Attached a helium balloon to my gas inlet for fun, this was the result.
"Get to the reactor!"
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Mark Rowley
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

Excellent work!!

"I occasionally hook up the 30kV precipitator power supply but haven't been able to get more than 4kv out of it when running it with the fusor, but with test loads it's fine."

Sounds like your trying to run it with too high of pressure. Once you obtain 40mTorr and below you should have no problem obtaining the higher voltages.

Mark Rowley
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Quaid Hawkins
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Re: Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

Thanks Mark, that was exactly the case. Getting just under 30kV out of it now!

UPDATE - August 12th 2020

I hooked up the turbo pump and after chasing some leaks, my thermocouple gauge to bottom out. I'm questioning whether I should run two gauges even though fusor operating pressure is withing my thermo's range. I do like knowing all the little bits of data about my system so I'll probably wait for a while until something cheap comes up...

The precipitator power supply give me ~27-29kV when operated around 10-25 micron. Enough to get plenty of x-rays. Don't know the current yet, 10 ohm 20 watt resistor coming in the mail.
Plasma(1).png


My next plan is to make all (most) operations remote. I have a handful of relays to control the on/off's. My turbo pump has a serial interface mode where I can control with my pc. Only hitch right now is the voltage control on the precipitator power supply. I plan on using the X9c103 digitally controlled potentiometer and control it with an Arduino. Basically just a bunch on resistors that it switches through, not as smooth but I can control it from afar.
https://www.renesas.com/us/en/www/doc/d ... 04-503.pdf

Will update on the rest of my efforts soon
Cheers
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Re: Quaid Hawkins - Plasma and Progress

Post by Cai Arcos »

Hi:

I've read that digital potentiometers don't like to operate in very noisy areas. Besides, taking into account that a failure of this component could be fatal, I would recommend connecting a phenolic (or other insulating material) to the shaft of the original potentiometer, and then this rod to a servo motor, which could easily be controlled by a micro.
Very nice system, btw!
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

Quaid,
Specific to a precipitator supply, current monitoring is more important than anything else...even voltage. Those supplies absolutely despise current draw spikes or really anything over 4-5mA. Cross fusors are notorious for unstable current draw spikes.

If you want your supply to survive, I highly recommend a full cessation of testing until you can properly and accurately monitor current.

The precip supplies are great if treated properly. They have enabled me to surpass a neutron TIER of 2E+06, but DEMAND certain cautions are strictly adhered to.

It quite possible some damage already occurred.

Mark Rowley
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Quaid Hawkins
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Re: Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

Cai,

I didn't know that about digital pots. Good thing too, I was just about to order them :p. I'm using an insulated rod to manually turn the pot right now anyways so rigging up a servo to turn it won't be too hard.


Mark,

Noted, I haven't run the fusor since my last (and only) run at >4kV voltages, which was only for about 30 seconds. I have two of the precip supplies so if one is irreparably damaged there's a backup. On that note, how would I know if some damage has occurred? Would it not be able to achieve full voltage? current?

The 10 ohm resistor came in, and will wire it up soon. Even with current measurement how would I prevent against current spikes? I thought the precipitator power supply was current limited and so ballasting was optional


Quaid
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Re: Quaid Hawkins - Plasma and Progress

Post by Mark Rowley »

The speed of a current spike (or voltage for that matter) can exceed the limitations of an analog meter. Even with a digital meter it could be easy to miss.

Best advice is to avoid firing up the power supply until you’re at around 50mTorr or below. Cross fusors generally operate in the 35-50mTorr range. Be very cautious and SLOW when adjusting deuterium flow with the needle valve. A very slight adjustment could be enough to drop the vacuum levels to such a degree that voltage can spike past maximum output OR if too much gas is let in, you could briefly dump more than 10mA into the system before the psu can recover.

As Richard and others have pointed out many times before, operating a fusor can be considerably more difficult and frustrating than building one. In all respects it’s a learned art form. It’s the main reason many push the use of a durable NST when learning how to gauge deuterium gas flow, voltage, and current simultaneously. It also allows you to safely learn how to react to the hiccups and burps a new fusor can have. Precips are not happy campers or forgiving with those conditions.

Try to use deuterium or helium when learning how to drive. Why? Because deuterium gas control is wildly different than using regular air. Helium may be a cheap alternative if you don’t want to use deuterium.

Most of this stuff is in the FAQ’s but precips are a newcomer. They require a few more considerations but can really perform when you get an operational understanding of their differences.

Mark Rowley
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Re: Quaid Hawkins - Plasma and Progress

Post by Dennis P Brown »

Mark gave great advice. In answer to your one question - you can't prevent a plasma current spike in a fusor. Impossible. That is the whole point of a ballast resistor and its function. To protect the power supply long enough so that you can get the system back under control before the transformer is damaged. The ballast resistor needs to be under oil (to further prevent arc's across it and as an effective coolent.) Richard has a FAQ on this - viewtopic.php?f=29&t=13497

My system uses a 60 k-ohm , 40 watt wire wound resistor under oil and works great. Notice the value - it isn't 60 ohms but 60 k-ohms as per Richards advice. A 10 ohm resistor is better than a short but might not be enough. Don't know what is necessary for the trype of supply you use. Others I would think know.
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Re: Quaid Hawkins - Plasma and Progress

Post by Quaid Hawkins »

Thanks for the advice, most of this is in the FAQs but I guess I was looking specifically in terms of the precipitators

I may have destroyed one of the precipitators, but I'm not sure yet. The turbo pump really sucks and if I open the throttle valve a hair too much the vacuum drops to the point where I can't strike a plasma, and the voltage jumps. All within a second. Or when I strike plasma the pressure increases by about 10-20 microns then drops again. The amount of increase is less every time I hit plasma. Maybe bakeout? Either way I have done some damage - hopefully not fatally

I have heard Richard talk about the difficulty of operation and the "feel" you have to have of your system. I am definitely realizing the difficulty of the that right now. Controlling pressure and power simultaneously into a stable state. I will hook up my NST to use while I practice controlling the pressure in the 35-50 micron range, and find some helium to use (never want to waste that precious deuterium). Will also acquire a ballast resistor to use later with the precipitators. The 10 ohm resistor is hooked up between the fusor shell and ground to measure current.

Quaid
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Re: Quaid Hawkins - Plasma and Progress

Post by Dennis P Brown »

I discovered that 'seasoning' my fusor made operation rather easy after it was open to the air. First, I pumped it down to the very low 10^-5 torr. Then flushed some deuterium through it and carefully adjusted the gate valve to get around 10- 25 microns. Then I'd raise my x-former up slowly. I'd try and strike a plasma. If I did I'd let it run a few minutes holding the pressuring that allowed this. Only then would I allow it to lower (by valving off the deuterium supply) to 5 - 7 microns. I found it was far more stable. I still could/would lose control (cut off or run away) but as these happen, they'd get more rare. After a few false starts, I easily ran my fusor for half an hour measuring neutrons - limited only by over heating (till I added water cooling; then I could run two hours no problem even if I had open it that morning.)

A proper ballast resistor is critical for protecting one's x-former/power supply.

If you are using a 10 ohm resistor be certain you are following Richards safety methods - don't want your fusor floating to lethal levels.
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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
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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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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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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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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 3764 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
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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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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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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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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
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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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