Use of a Precipatator Power Supply

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Joshua Guertler
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Re: Use of a Precipatator Power Supply

Post by Joshua Guertler » Tue Aug 07, 2018 1:04 pm

Greetings Mr. Hull,

For operator's skill, please assume that the operator is a first-time fusor maker who will be working from all ranges between 1-20 mTorr. I am just curious on whether or not I should be using a 6" sphere or a t-shaped chamber for my fusor. Thank you.

Sincerely, Joshua Guertler

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Re: Use of a Precipatator Power Supply

Post by Jake Wells » Tue Aug 07, 2018 2:53 pm

Joshua,

You keep asking what kind of neutron output you will achieve under "ideal" conditions and you keep getting the same answer: Nobody knows! Also could you give more information on your chamber. How many ports does it have? What is the inside diameter of the T-shape? If it were me I would go for the 6" spherical chamber. You keep asking a question that has been addressed several times in the FAQ's.
“The day science begins to study non-physical phenomena, it will make more progress in one decade than in all the previous centuries of its existence.”
― Nikola Tesla

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Richard Hull
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Re: Use of a Precipatator Power Supply

Post by Richard Hull » Tue Aug 07, 2018 3:46 pm

Operator skill sets are accumulated very rapidly if superb instrumentation is at hand and the operator has a familiarity with ionized gas reactions to the application of varying amounts of electrical energy, as in a demo fusor. Most amateur fusioneers never acquaint themselves intimately with ionized gases and never seem to be properly instrumented across the broad range of what is needed, mostly due to costs and a feeling of youthful urgency to just get fusion done. This low regard for such details tells in the rapidity with which people arrive here and leave here with zero results.

A quick dabble without quick results foils 99% of all attempts as the youthful bravado gives way to the myriad of other things impetuous youth could be doing outside of a tough uphill battle to do fusion which, for many, would just give them bragging rites.

Lack of funds stops a large fraction arriving here. The tedium of what comes to be perceived as long haul takes out a lot of the less driven. School, college and the discovery of girls also completely diverts or, more often ends the fusion quest.

Not oddly, most of the efforts here are begun by boys 13-18. Lots of youthful curiosity at a time when males are still found with a bit of free time and boundless enthusiasm. Many such males are special in the sense that they are headed into what they hope is a scientific future. This often means an ever more rigorous high school effort and a bone crushing college effort as getting an engineering, or physics degree is nothing like trying for a degree in social studies. Those fortunate to have family structures and parents willing and well off enough to support a fusion effort, who stick with the fusion effort to a fully successful conclusion are rare and are special young folks, indeed. They will take one of two paths in life. The first is that they are destined to become mover's and shakers in a future society. They are the discoverers, the leaders, the hustlers, they are those who are destined to rise to the top as they seem driven with energy and accomplishment that has no end until the grave. The other path is like that of a brilliant meteor that gleans awe and amazement when seen by all, but at some point on the upward move, they burn-out. This "burn-out" can come before finishing a grueling college effort or in mid-career or near the end of one.

Yes, a bit philosophical near the end here, but it points out why the success to failure ratio is near 1 in 100. It is no shame to fail here as most have bitten of a bit more than they can chew, often through no real fault of their own beyond boundless enthusiasm that can't, in the end, be funded, or due to frightened or disinterested parents, teachers or schools.

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.

Chris Giles
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Re: Use of a Precipatator Power Supply

Post by Chris Giles » Tue Aug 07, 2018 10:58 pm

Regarding the question about the suitability of the precipitator PSUs, I had been wondering the same especially after my initial rash purchase of an inappropriate precision unit.

There is an older thread on the forum discussing this here: viewtopic.php?f=11&t=11474&start=20#p77717. I’ve also seen this post by some chap playing around with one: https://3.14.by/en/read/hv-cupply-CXDZ-60kV-20N60C3

All of the units I have seen seem to be from this manufacturer: http://www.cxdz001.com/

In both of the above posts the point is made that in these units neither side of the DC output is grounded, unlike all the other PSUs one can find which are invariably negative ground. In theory you could ground either side of one of these to make a + or – DC supply, however, it seems the transformers and PCB are not rated to take the full voltage vs ground, rather expecting both positive and negative to be floating wrt ground (or rather the primary circuit). That seems very inadequate as far as safety goes since it could arc from the HV to the primary side. This is what has been reported in the 2nd post “..if you tie one of HV terminals to ground […] hottest transformer inside supply is much easier to breakdown. This is exactly what happened”.

CXDZ show a variety of PSUs in their range, some close, but none is quite right. I think it might be worth emailing them and saying exactly what would be ideal. They have a comment saying that customisations can be made. CX-600A is perhaps closest if instead of 2 x 30kV 10mA in series it could be 30kV 20mA.

However, I think it would also be sensible for this PSU to be overrated, i.e. it not be run near 100% of its rated voltage. As a comparison I noticed that inside a Matsusada PSU, it had neon bulbs all over the place as over-voltage safeguards. These units don't seem to have any. Another customization which would be useful (safe) is a remote control of the voltage. I think it would need to be a wireless (radio) solution to be safe with this thing! Emergency-off obviously can be a line voltage relay / switch.

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Re: Use of a Precipatator Power Supply

Post by Joshua Guertler » Thu Aug 09, 2018 3:16 pm

Greetings,

Thank you for the mention of the sources, they were very helpful to look over the source. Interestingly, the second post seemed to express a similar problem noted by Finn Hammer in a post which I included at the beginning of the topic (the issue having been coronas at ~20 kV). I too had this problem with the CX-300 PSU that I bought and examined what the issue could be. After a while of searching, I deduced that his was a result of poor insulation on the primary side of the transformer units as well as a poor potting job - as should be expected for a 70$ USD Chinese power supply.

However, I was able to fix this small issue by removing the insulation from the primary (which turned out to be some Teflon-looking tape) and potting it with 1/8¨ HV epoxy. On top of that, I added another 1/8¨ of HV putty rated for 550 VAC/mil. This potting option did not come cheap, but it worked like a charm.

After a bit of chiseling, I managed to remove the transformers from the PCB and placed them in a vat if mineral oil where a 10 AWG wire was used to make the connection to their original spots. I did not put the entire device under mineral oil, as there are quite a few caps and transistors with exposed high-gauge terminals on the low-voltage side that could easily be damaged by the rather corrosive oil. This should help the transformer overcome the problems discussed by Mr. Hammer and the arcing in your previous link, which could also very well be because the resistor that the individual cut actually had some protective purpose (mini ballast?).

I am currently purchasing a 5-60 kV DC, 400 Watt version of the source known as the CX-600 for a little over 200$ USD, however, I am only looking to run it at 40kV and 8-10 mA to avoid any adverse effects related to hitting the maximum current and voltage. If Mr. Hammer´s success with his source (the CX-300) in terms of its ability to draw 18 kV DC and 12 mA continuously for 10 minutes with no adverse effects (beyond a temperature rise of 15 degrees in the heat sink), my new source should be able to draw sufficient current and voltage to do some fusion under the fusor´s load. Since the only issue that Mr. Hammer noted as preventing his device (CX-300) from drawing the maximum voltage was the hissing corona and my adjustments seemed to have solved that, I would bet that I will be able to increase my output voltage to a sufficient amount to produce a neutron population detectable by a Ludlum 12-4 neutron counter. However, it should be noted that a HV diode (50 kV DC, 1 A), a source of inductance (possibly an MOT with the secondary shorted, as they will typically have an inductance of 68 mH), and a ballast resistor (the likes of which I am still fiddling around with) will be very necessary to prevent any sort of surges that could damage the device.

But hey, if it does not work out for fusion, I could get a nice look at plasma... maybe even in the PSU!

Sincerely, Joshua Guertler

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Re: Use of a Precipatator Power Supply

Post by Chris Giles » Fri Aug 10, 2018 9:26 pm

Oh yes, looking again at M. Svarichevsky’s post he does say “Initially power supply was limited to 42kV for reliability reasons. Manufacturer gave instructions how to unlock full 60kV (that requires cutting 1 resistor inside).”, so maybe running the CX600 below 40kV would be fine. Perhaps worth emailing them to see if it is rated to last while having one side grounded.

How about potting the HV side of the board in-situ without removing or disassembling the transformers? I’m not at the stage of needing the HV PSU yet so I will be interested to hear back about this PSU.

FYI, this comprehensive document from Spellman is very useful.

Out of interest, Svarichevsky has some interesting posts on his site, but so far hasn’t quite taken on the challenge of making a Fusor!

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Re: Use of a Precipatator Power Supply

Post by Joshua Guertler » Fri Aug 10, 2018 10:31 pm

Greetings Mr. Giles,

Thank you for looking at my post, it's the first of many entries (I hope) to document the progress on my fusor.

To address your first question, I did end up messaging the sellers of the CX-400 and the WYS-600 a while ago on eBay to ask if they could comment on a few of my questions. Both of the sellers contacted told me that at full power and voltage output with the positive terminal to ground (0 V), both power supplies will last 8 hours when running continuously. However, they did tell me of a couple strict conditions. First off, there may be a gap no larger than 6 cm between the inner and outer grids for the 8 hour period. Also, they both stressed that the transformers must be kept cool- whether it would be in mineral oil or via the cooling unit sold with the product. The company also recommended that I submerse the transformers in mineral oil, as arcing likely once you pass -20 kV DC. If you can, keep the included fan and use it to cool the rest of the PCB, as that will get pretty hot if you try to go for the full 8 hours!

As for your second point, I would not recommend potting the entire HV side, as there are a few transistors and components that would not perform properly in a potted environment due to over heating and would probably lose their terminals in mineral oil. I myself originally wanted to pot the entire HV side in a HV dielectric epoxy and reached out to the seller for his opinion. He told me that with such a high power being pumped through the four flybacks, the HV section will put out a lot of heat. Thus, an active cooling system is needed to get rid of this heat - hence, the giant fan in the eBay pictures. Unfortunately, most affordable potting solutions (such as epoxy) would only trap the heat and lead to a cascade of problems after time.

One thing that I am curious about is the stability of the output due to the change in resistance that occurs when the fusor begins to produce plasma. Also, I was curious what the maximum acceptable voltage ripple would be for a fusor, as I am worried that it could be on the 400 V side of things when it turns on. Just in case, I will include a ballast resistor and possibly some caps and inductors to smooth out the voltage. Also, I would recommend putting something like a MOT on the low voltage, AC side to act as an inductor to prevent excessive current draw. Basically, you would do this by connecting the live wire to the MOT primary and have the current come out of the other terminal in the primary and then short circuiting the secondary output to itself. But be warned, don't mess around with MOTs if you don't know how to properly deal with high voltages (especially AC). I have only heard of people being shocked once by MOTs.

And by the way, thanks for the Spellman link! It'll be quite a nice resource as I continue to build my HV system. I also think that it's a great safety resource for anyone who is new to HV components and sources.

Sincerely, Joshua Guertler

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Re: Use of a Precipatator Power Supply

Post by Chris Giles » Sat Aug 11, 2018 12:07 am

Hello Joshua.
Both of the sellers contacted told me that at full power and voltage output with the positive terminal to ground (0 V), both power supplies will last 8 hours when running continuously.
So I assume they mean that after 8 hours some components (e.g. the transformers) are likely to fail, perhaps have the insulation break down. It would be useful to know under what conditions it is rated to operate for a decent length of time i.e. thousands of hours. These are marketed to be used in an industrial environment where I would have thought they would run for a very long time and probably continuously. Maybe if the PSU is run for a shorter continuous period such as half an hour, it could do that day-in-day-out, otherwise maybe it can last properly at a lower output voltage.

In the Matsusada PSU I had, the entire HV output stage was potted but i think that in that it may have been just a multiplier not a transformer. It does seem like the transformers in this are being pushed too hard both in terms of the voltage (insulation breakdown) and the power (overheating).

Cheers
Chris

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Re: Use of a Precipatator Power Supply

Post by Joshua Guertler » Sun Aug 19, 2018 10:08 pm

Greetings,

I hope that I'm not talking into a dead thread, but I have a small question that may help myself and any others on this thread looking to produce fusion using a precipitator as a power supply.

I found on an old post some time ago Mr. Hull voicing this concern that these sorts of power supplies may act relatively erratically during the process of establishing plasma in the fusor, a concern that I will also second. In order to combat this concern, I was curious if a MOT transformer could be set up to act as a current-limiting ballast on the AC side of the power set up (before the precipitator power supply) on the live wire. This would basically work by setting up the primary side of the MOT in series with the primary side of the power supply. Of course, the secondary side of the MOT is shorted to itself. Please check out the included link to see a visual description: http://robofusor.haylett.ca/robofusor-2 ... wer-supply. Also, please see the added attachment for the original schematic.

Hopefully, the previously mentioned design should be able to prevent an overly high current 'cascade' when the device gets turned on. However, I am quite hopeful after hearing that Mr. Shireesh Apte managed to use a smaller version of my power supply to form plasma at 100 microns (viewtopic.php?f=11&t=11474&p=77652&hili ... tor#p77652).

In order to further secure potential success with this design, I was curious what I could do to initially establish a plasma in my fusor before the HV was added from the precipitator. My hope for this is to establish a conductive plasma to prevent any sort of strong current 'swing.' I was initially thinking that ion guns may do the trick, however, I am not sure if they would have the needed plasma production without slapping on another precipitator. Thank you.

Sincerely, Joshua Guertler
Attachments
ALt. HV design.JPG

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Re: Use of a Precipatator Power Supply

Post by Chris Giles » Thu Aug 23, 2018 10:46 pm

I hope that I'm not talking into a dead thread,
I hope not.. I'm looking forward to hear back about how this works out in practice!
... concern that these sorts of power supplies may act relatively erratically during the process of establishing plasma in the fusor, ..
I guess this may be a concern with a PSU which has an over-current cutout. Maybe the impedance of the plasma varies erratically? This could cause a regulated PSU to keep cutting out. Best answered by someone with some experience of this...
I was curious if a MOT transformer could be set up to act as a current-limiting ballast on the AC side of the power set up (before the precipitator power supply) on the live wire.
No, definitely not. These are Switch Mode PSUs. They first rectify the 50/60Hz mains to DC then chop it up at a high frequency, typically about 50kHz. This allows the use of a much smaller transformer for a given power. See this reference from MicroChip for example. or this from ON Semi. Regulation in such PSUs is achieved by a feedback loop from the secondary circuit back to the SMPS driver. In a non-HV type this may use opto-isolators. See p30 in the first reference for a general description. The design is one of the isolating type shown in the docs (flyback, forward, push-pull etc) rather than buck/boost.

The Spellman doc does describe that their PSUs do this:
With the output of the supply ground referenced it is easy to sample the output voltage and current to obtain the feedback signals needed to regulate the supply. A high impedance, ground referenced, high voltage feedback divider monitors the output voltage, while a ground referenced current feedback resistor placed in series with the multiplier return monitors the output current.
The circuit in the CXDZ PSUs is clearly a very basic one. Usually SMPS are much more complex than this. As I mentioned, the Matsusada one i saw was enormously complex. Nonetheless, i'm sure it must have some feedback loop. It does have an optional current limit switch. I suggest you dont need to worry about this... just try it out. To start with I'd turn the current limit on. See if it is basically working, then turn it off if it keeps cutting out.

BTW, the output looks as though it is not smoothed, so it will give half-wave or full-wave AC at the switching frequency not DC. I guess there is no need to smooth it for a fusor but it may need to be taken into account when measuring the voltage with a meter. DC meter will read the peak voltage. AC setting would measure the RMS voltage as Peak Voltage * 1/sqrt(2). Same applies to the current measurement. Adjust to RMS for calculating the power dissipated.

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