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Registered Member #125
Joined: Fri Feb 10 2006, 01:52PM
Location: Aalborg, Denmark
Posts: 155
Hi all,
I'm in the mechanical design stage of the big CW multiplier, and I need to simulate the field around it. I've seen the glassman multipliers have balancing rings all the way op to the top load, and I need to do the same to avoid flashover and loss. I've also had a look at a paper with a neat little 500kv CW to drive a photocatode DC gun, with the same principle.
I can't guess my way out of this, and need to do a simulation to see what happens...
I tried to download inca from Carlos website, but it seems to be down at the moment.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
FEMM is the most popular simulator.
I think any kind of grading rings will be better than none. The main purpose of them is to prevent corona by shielding the sharp corners and lumpy components that make up the CW stack itself.
There are two variables: how thick do you make the rings and how many/how far apart.
If you make them too thin, the E-field at the surface of the tubing will be excessive. Too thick, and the E-field in the remaining space between them will be excessive. Eyeballing the thickness of tubing used in the Glassman ones would be a reasonable start.
The spacing of the rings on the Glassman stack is uneven. I think this is simply because there is one ring per stage, and the bottom few stages have more caps and take up more room.
As far as I know, they are all connected to the output capacitor stack at their respective stages.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I'm wondering, have you given any thought to the issue of preventing diode flash-over?
In the case of 2CL2FM diodes (and I think it applies to the smaller diodes as well) I was told by the manufacturer that they need to be encapsulated in something.
Registered Member #125
Joined: Fri Feb 10 2006, 01:52PM
Location: Aalborg, Denmark
Posts: 155
jpsmith123 wrote ...
I'm wondering, have you given any thought to the issue of preventing diode flash-over?
In the case of 2CL2FM diodes (and I think it applies to the smaller diodes as well) I was told by the manufacturer that they need to be encapsulated in something.
No I haven't yet, I will make five stages as a test setup when the diodes arrive, and if it becomes a problem I will put them in a tube and fill it with epoxy. I have all the things at work to do such things:-)
Steve,
I will take a look at FEMM this weekend, and try to make some simulations. I don't think that the rings is connected to anything, they are just floating and is there to control the field.but I have to investigate that, as I really don't have a clue about it.
I will start the build next week, and then we will see what happens:-)
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The best (free) electric field simulator?
