Power Source Voltage Ripple Regulation

For Short Term Learning Discussions ONLY. This area is for CURSORY questions and connecting with other users ONLY. ALL technical contributions need to be made in the appropriate forums and NOT HERE. All posts are temporary and will be deleted within weeks or months. You should have already search the extensive FAQs in each of the forums before posting here as your question may already be answered.
Post Reply
The Super Nerds Team
Posts: 11
Joined: Sat Jul 14, 2018 8:13 pm
Real name: The Super Nerds Team

Power Source Voltage Ripple Regulation

Post by The Super Nerds Team » Mon Sep 10, 2018 7:34 pm

Greetings,

After getting to meet with and talk to Joshua Guertler - another Fusioneer-to-be - the rest of the Super Nerds Team and I became interested in using an electrostatic precipitator power supply as the main power supply for our small-scale fusor. Due to our relatively large budget, the team was able to afford a relatively expensive power supply that has been claimed to be able to supply 600 Watts and -60 kV DC at the pressures which the fusor operates at, whether or not this is true will be tested. I have included a link to the product for those who are interested to see the eBay product that we are referencing: https://www.ebay.com/itm/High-Voltage-E ... 2405889314.

With the design, there have been a couple of issues that we want to make sure that we solve before getting the supply to power the fusor. First, we decided to remove the four flyback transformers in the power supply and submerse them in mineral oil to act as De Facto transformer oil. Each transformer and its connection will be given silicone insulation to minimize any damage on exposed electronics from mineral oil. While Joshua Guertler told me that this approach should work, I would like to confirm with the fusor community that this approach for a flyback transformer would be safe.

The other potential issue that the team has - and the cause for positing this question - is that people on this forum in the past have noted that the output of these sorts of electrostatic precipitator power supplies produce a relatively ripple-heavy DC output, as the power source relies on flyback transformers and following diodes for rectification. This has been explained in one of Finn Hammer's write-ups about his assessment of a 200 watt and 30 kV DC precipitator power supply seen here: viewtopic.php?f=11&t=11992&p=78210&hili ... ese#p77912.

To combat the problem, I have been considering the apparatus set up shown as an attachment to this post. Since I do not know the frequency or the peak voltage of the ripples from the team's power supply I did not assign a capacitance to the capacitor. The apparatus shows an input voltage of -40 kV DC, as I am not certain that the device can supply the advertised -60 kV DC safely (just a suspicion from a long-time buyer of Chinese electronics). Having experimented around with similar power supplies from the same seller, I have seen that you can exceed the 10 mA output when operating below -60 kV as long as you turn off the current control mechanism which will effectively act as an adjustable ballast resistor to prevent current cascades when you turn up the power. Hopefully, this should put me at around -40 kV DC and 10 mA with ripples. Again, I am not certain about the frequency of the ripples, but I would assume that they are proportional to the ones seen in Finn Hammer's experiment once the fusor's plasma stabilizes. If fusor would work well regardless of the voltage ripples, please make sure to address this to my team and I, as we have generally seen from the forum that such ripples must be dealt with.

On a similar note, my team and I have seen quite a few remarks from others that such a power supply might not be able to function under the conditions provided by a fusor's plasma due to the strong swings in a fusor's internal resistance. Thus, we were curious if there was a relatively inexpensive way that we could fix this problem with out power supply by making certain that a constant and stable current output could be provided. Please keep in mind that the current-moderating capability of the power supply can be turned off completely and gradually decreased, so there is no concern of the power supply shutting off upon establishing plasma.

Also, we were curious if there was a way for us to inexpensively establish an environment where the establishment of plasma would not cause such a strain on the power supply's current output. This could be something like incorporating an accelerator-type design or ion gun to prevent a massive strain on the power supply.

Thank you.

Sincerely, Zach from the Super Nerds Team
Attachments
4bc.jpg

User avatar
Dennis P Brown
Posts: 1510
Joined: Sun May 20, 2012 2:46 pm
Real name: Dennis P Brown
Location: Glen Arm, MD

Re: Power Source Voltage Ripple Regulation

Post by Dennis P Brown » Tue Sep 11, 2018 10:09 am

Someone did, if I recall, not too long ago try one of these exact units and they haven't posted since. There may be issues that cause problems - placing the unit under oil can't hurt but you might consider placing the unit under vacuum first, then adding oil so there is no trapped air within the cores. I plan on doing that with my new 60 kV xformer when I have time later this winter. That shouldn't be very difficult to setup and do.

I am suspicious of transformer systems that are placed in parallel for extra current and I seriously wonder if they can maintain the load in any real balanced manner - an expert EE once warned me that in most resistive circuits that are parallel, 99% of the current goes through the device with the very slightest lower resistance and the others carry little - if they are using a phase system, maybe it will work but again, requires a good design - maybe it is and maybe not.

If one has the funds, why not just obtain a proper power supply or at least a proper transformer and build a supply?

If you already have it, I guess it can't hurt to try but a good ballast resistor would appear essential - that is the only "inexpensive" method I know that will help control the swings within the fusor. Not sure that issue can be overcome if the unit shuts off during swings - that just makes matters more difficult, from what I've experienced dealing with swings. Having a power supply that can handle the current run-aways allowed me to establish a steady plasma by careful deuterium, and voltage control during the swings. I quickly and easily established a good, steady plasma. If my unit was cutting out, not sure that would have been so easy.

Well, hope you succeed because that would be a very useful development for fusors and people wanting to try their hand at this - since the cost of a power supply is, without a doubt, one major drawback.

The Super Nerds Team
Posts: 11
Joined: Sat Jul 14, 2018 8:13 pm
Real name: The Super Nerds Team

Re: Power Source Voltage Ripple Regulation

Post by The Super Nerds Team » Wed Sep 12, 2018 2:00 am

As a quick question to the general community, would this power source even need a capacitor set or device of the sort to smooth down the current ripples, or would a ballast resistor followed by a HV diode do the trick?

Post Reply