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Andy

Thu Dec 13 2012, 03:15AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

I'm trying to create a magnetic pinch, below is some off the experiments I've done.

The coil is 40+30, with both south poles facing each other, the camera has a burning effect moving the spark outside the pipe.

This was with a 0.047uF cap measured from a multimeter at 20kv

Try a test with two mag same poles facing each other. It hasn't done what the top did, i'm guessing its the heat and amps that expands the air that force the plasma to follow the magnetic field.
This was with a 76pF cap measured from a multimeter at 20-40kv

This was with 0.006uF cap at 20kv,Will try the same setup but with 60-80kv when the parts arrive
The positive is connected to the larger diameter coil

The ground is connected to the larger diameter coil

Andy

Fri Dec 14 2012, 01:37AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Theory post

Electrical conductive of a arc discharge, voltage drop across a arc, V = (I/A)(AR/d)(d)
Current in the arc as j =o*E ,o =E/j
o = 3Ã—10âˆ’15
E = 20kv
j = 0.00000000006amps

Force on a charged particle, Fe = e*E+j*B
e = 1.60E-019
E = 20kv
j = 0.00000000006amps
B = 0.68Telsa
Fe = 0.0000000000408joules(2.5465e+8ev)
KE = 2.5465e+8

Andy

Fri Dec 14 2012, 04:14AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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blank

Ash Small

Fri Dec 14 2012, 09:13AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Any chance of some bigger pictures of that twisting arc, Andy?

(BTW, you ought to be updating the first post with progress as you go. It's fine using subsequent posts as you go, but progress should be posted in the first post using the edit function, so that people don't have to scroll through a long thread that could be pages and pages in order to see how the project is developing)

Andy

Thu Dec 20 2012, 07:20AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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What pump could you use to make a vacuum?

Ash Small

Thu Dec 20 2012, 08:51AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Andy wrote ...

What pump could you use to make a vacuum?

This depends on how hard a vacuum you require, but generally you'll need two pumps, a 'roughing' or 'backing' pump, eg a ratary vane pump, and a 'high vacuum' pump, either a diffusion pump or turbo-molucular pump. (for very high vacuums you'll also need an 'ion pump', or similar.

Turbo-molecular pumps are expensive (although there are occasional bargains on Ebay), fragile, and require expensive controllers (there are a few guides on the 'net for building your own).

I'd recommend a cheap diffusion pump from Ebay, and a rotary vane backing pump (diffusion and turbo pumps won't work at atmospheric pressure, they only work at pressures in the 'molecular flow' regime, so you need the backing pump tp 'start things off, and to 'back' the diff/turbo pump.

If you are in the US you probably want to be looking out for a Welch rotary vane pump, probably belt driven, if in UK, an Edwards unit.

Similarly, Veeco diff pumps seem easier to obtain in the US, and Edwards ones in the UK.

A two inch diff pump will be plenty large enough, smaller will probably do, but they are less common. Larger ones require more 'expensive' oil, and consume more power.

You'll also need vacuum guages, plumbing, etc. (and some form of 'chamber').

Daedronus

Thu Dec 20 2012, 09:35AM

Registered Member #2329 Joined: Tue Sept 01 2009, 08:25AM
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Mechanical pumps are good down to micron (10^-3 torr) pressures (assuming they are in good condition with clean oil).

If you plan to use a diffusion/turbo pump the mechanical pump just needs to be large so it evacuates fast, it doesn't matter if it will only get to 100 microns.

Diffusion pumps need foreline pressure below 500 microns, more or less, it depends on the oil.

For a diffusion pump you also need a foreline trap (it can be just some copper sponge, anything that is vacuum compatible and is optically opaque) or the mechanical pump oil will eventually contaminate the oil in the diffusion pump.

From my experience I will tell you not to cheap out when it comes to vacuum seals, only use metal, or viton seals.

Andy

Thu Dec 20 2012, 06:08PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Would this be a good pump

, The turbo pumps are out of the price range. Is there any glue that could handle vacuum joining two perplex plastic together, would plain steel be alright for the chamber.

Daedronus

Thu Dec 20 2012, 09:58PM

Registered Member #2329 Joined: Tue Sept 01 2009, 08:25AM
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A dry pump will not reach too much or a vacuum.

They can be used with a tubomolecular pump to get a 100% clean vacuum, since there is no oil. Oil in mechanical or diffusion pumps can reach in small amounts intro the chamber.
This can be stopped to large degree using optically opaque baffles.

But keep in mind that diffusion pumps are fine even for things like electron microscopes.

You would want a 100% oil free system if you make microprocessors or something, not common things.

What is your pressure target? that's the key question.
I know the thread is about a plasma Z pinch, but I have no clue in what kind of vacuum you want to use it.

Andy

Thu Dec 20 2012, 10:39PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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I'm not sure the temperature of the arc, 2 psi should be alright i think. If I can get it down near there it will be cheaper to build a large cap than go lower in pressure.

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