User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.6.1
On 2/7/23 9:08 PM, Ian Gault wrote:
Hello,
I’m interested in replicating David LaPoint’s ‘Primer Fusion’ project.
This is my first plasma project. I have been working with high voltage
impulses up to 7kV regularly, but am asking advice on the best way to
build a psu providing ~500,000v.
That's quite a challenge, mostly from the mechanical side - insulating
500kV is not easy, especially things like avoiding corona.
in air, uniform field breakdown is around 30kV/cm (70 kV/inch) (round
numbers), but the field isn't uniform on most HV gear.
All your conductors need to have big radii of curvature. Immersing in
oil or SF6 helps a fair amount, but brings with it a bunch of other
difficulties (leaks, mess, etc.)
I plan to use a Cockroft Walton multiplier in 20-30kV steps, but need a
psu to provide 20-30kv to the first stage.
Yes, that works - Take a look at the C-W generator pictures in museums
(there's a nice one at the Scottish National Museum in Edinburgh)
that's 1 MV and fairly old technology for the HV rectifiers, but it is
air insulated, and gives you an idea of the size needed to get insulation.
Tesla coils get up to around 500kV, but you'll note they generate
copious ozone (indicating corona) and, of course, have sparks into free
space.
The main difficulty I’m having is that I want to be able to manipulate
the:
1 – Voltage 0-500Kv
Varying 0-500kV with a single knob is possible, but more likely you'd do
it with various taps (add/remove parts of your CW stack, for instance)
2 – Phase
The CW is a DC output device, maybe what you want is a cascade transformer?
3 – Polarity
You can reverse the rectifiers in a CW and flip the polarity. Not with a
switch, but more like by restacking it.
4 – Frequency
What range?
5 – Duty (possibly)
This would require amplifying the input signal without altering its
nature.
that's really, really hard.
You didn't mention what current you need. Microamps? Milliamps?
It looks like ZVS into Flyback tx’rs will only work on specific
frequencies, so could a NST work?
A NST will do a nice job of getting you ~15kVrms from line voltage, with
some limitations. you could drive it with variable voltage and
frequency (within limits).
I plan to use an existing system I have with dual channel signal
generator to control freq, phase, and duty into dual gate drivers/HV
Mosfets for impulses, but also require a continuous power feed as an
alternative.
If you're doing AC, then a cascade of transformers might be a way to get
what you need. The classic way is to have transformers with multiple
windings and really good insulation. Say you want 500kV. If you have 5
transformers that have 100kV output (and insulation to match), you run
them in series. The trick is how do you get primary power to the
transformers at the top of the stack? Say your transformers are 20:1,
5kV in and 100 kV out. The bottom transformer has 3 windings, 2 for 5
kV, and one for 100kV. One of the 5kV windings is insulated for 100kV.
You feed the low voltage 5kV, take the higher insulation voltage 5kV and
feed it to the next transformer up the stack, which sits at 100kV above
ground potential.
Any advice would be greatly appreciated.
Many thanks,
Ian.
Sent from [1]Mail for Windows
References
1. https://go.microsoft.com/fwlink/?LinkId=550986
_______________________________________________
Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx
_______________________________________________
Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx