Diy linear accelerator

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John Futter
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Re: Diy linear accelerator

Post by John Futter » Wed May 27, 2020 7:19 pm

Sarmad
Thank you for posting the neon transformer specifications

just note that the transformer is 120 watts input so output less because of losses in the circuitry

the output claimed is a little misleading as they are trying to say its 360 watts output

not so ----neons need lots of volts to strike then settle to much lower voltages to run hence the 12kV but the run for a neon tube is 100 - 1000 volts depending on length and diameter

so running 1000 volts @ 30 mA gives 30 watts -- a clue is neon tubes run warm not hot ie a few watts / per foot

be careful that little black box will not last too long at continuous high power output

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Dennis P Brown
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Re: Diy linear accelerator

Post by Dennis P Brown » Wed May 27, 2020 7:31 pm

The vacuum requirements for a linac (or any drift like linear accelerator) is very high - for a moderate length, 10^-6 torr is mandatory; otherwise, collsions will cause the gas molecules in the tube to scatter/ionize preventing any acceleration of your desired ions. No two stage pump will work alone. You need either a turbo or a diffusion pump (DP) with a trap and approperate gauges. This isn't easy - I built one. The required high vacuum is very difficult to achieve with couplings (been there, done that.) Your -30 inch of Hg indicates you are rather new at vacuum work. Units here are generally torr and negative inches is, to say the least, a rather nonsensical unit if you think about it.

Sarmad suseyn
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Re: Diy linear accelerator

Post by Sarmad suseyn » Thu May 28, 2020 12:17 am

Hi dennis
Thanks for the information. I agree with regarding the turbomolecular pump . You said you already did it before. Can you share some information .about the build.
Thanks

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Richard Hull
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Re: Diy linear accelerator

Post by Richard Hull » Thu May 28, 2020 7:20 am

Like pretty pictures of a complete system build? Try this obvious FAQ with captions and explanations. This system uses a diff pump, the absolute least expensive secondary pump. READ all the FAQs on all subjects!

viewtopic.php?f=24&t=13055

More pretty pictures of a complete recent build using a turbo pump (spread over 5 pages). A fabulous vacuum system build using a list price $5000 turbo pump and controller. Terrible fusor, however.

viewtopic.php?f=6&t=13176

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.

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Rich Feldman
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Re: Diy linear accelerator

Post by Rich Feldman » Thu May 28, 2020 12:31 pm

Couple more points.

Sarmad's original statement of vacuum was not -30 inches, it was more than twice as strong: -30 psi.

The neon sign power supply does _not_ have two terminals, There are at least four, if we count AC power input and maybe ground.
Here is why those matter, and schematic is incomplete without them.
It is important to know the electrical connection, outside the drift tube, between DC and AC power supplies.
(As we see in the Lawrence and Sloan figure, which also features thick connection to vacuum pump.)
Otherwise the relative potential is undefined. Actually it would be determined by internal particle currents and external leakage.
All models are wrong; some models are useful. -- George Box

Sarmad suseyn
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Re: Diy linear accelerator

Post by Sarmad suseyn » Thu May 28, 2020 12:47 pm

Dear rich
The hv ac power supply have the total 5
Input 3 L ,N AND Ground
Output 2
This what i have in it.

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Dennis P Brown
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Re: Diy linear accelerator

Post by Dennis P Brown » Thu May 28, 2020 6:13 pm

Well, rather than make you search through my far too many posts on the subject (I really bored everyone on that score; sorry) here is a link to pics of the device - it is fairly big and there are a number of pics:
viewtopic.php?f=18&t=9359&p=63240&hilit ... tor#p63240

Again, use either Pa or Torr (preferred here) for vacuum units and never use negative units. That is very sloppy and are not really valid (sorry engineer's but that is just the way it is.)

Negative 30 psi for a vacuum is physically impossible - think about that and why, Rich (unless, maybe, we are talking dark matter? ;) .)

Now there are vacuum gauges that display -30 inches of Hg so that is what I assumed he really meant and just mistyped getting psi.

A small deuterium or other ion gun is a worthy project and if you can get a turbo, well worth the effort; I'd suggest stay away from accelerator level devices [requiring stages (i.e. couplings! The bane of high vacuum!)]. My such device did not turn out well for me - lol. My issue was the accelerating field - not the vacuum (but that took a long time to get right.) I will, time permitting, revisit that old work if I get time once my new facility (i.e. overbuilt out door shed) is contructed.

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