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Author Topic: Can an electromagnet repel ionized air molecules?  (Read 13450 times)

Offline starwarsmat

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I am currently working on a project, but before i build my device I need to know if one could use an electromagnet to repel ionized air molecules. If this is possible could you also show me a formula that would be used to calculate the acceleration achieved by the repulsion of the ionized molecules.


 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #1 on: 19/03/2015 08:15:53 »
I am currently working on a project, but before i build my device I need to know if one could use an electromagnet to repel ionized air molecules. .....

Ionisation is an electrostatic effect not a magnetic one.
You could use charged plates to attract or repel the ions.
 

Offline Thebox

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Re: Can an electromagnet repel ionized air molecules?
« Reply #2 on: 20/03/2015 23:54:41 »
I am currently working on a project, but before i build my device I need to know if one could use an electromagnet to repel ionized air molecules. .....

Ionisation is an electrostatic effect not a magnetic one.
You could use charged plates to attract or repel the ions.

Like a charged tectonic plate? or a charged core?
 

Offline chiralSPO

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Re: Can an electromagnet repel ionized air molecules?
« Reply #3 on: 21/03/2015 01:25:32 »
A magnet will not repel charged particles, but it will deflect them. The force on a moving charged particle will be at a right angle to the direction it is moving in. In a uniform magnetic field, charged particles will ultimately move in circles.
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #4 on: 21/03/2015 08:14:35 »
A magnet will not repel charged particles, but it will deflect them. The force on a moving charged particle will be at a right angle to the direction it is moving in. In a uniform magnetic field, charged particles will ultimately move in circles.

You're right, in trying to answer the top level question of repulsion, I forgot to ask OP what his project is. He might just be trying to contain the charges.

Starwarsmat, can you describe your project please?
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #5 on: 21/03/2015 21:12:47 »
My project is to create a device that will accelerate the air ions in one direction and to calculate their acceleration. If a charged metal plate would be the only way to do this could one of you tell me a way to accomplish this or to link me to a place that will. also would coulombs law be the only formula for this or are there others to also use.
 

Offline evan_au

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Re: Can an electromagnet repel ionized air molecules?
« Reply #6 on: 21/03/2015 22:03:31 »
Quote
My project is to create a device that will accelerate the air ions in one direction and to calculate their acceleration.
To see how the charge on the electron was originally measured, see: http://en.wikipedia.org/wiki/Oil_drop_experiment

Air is (mostly) an insulator, so it is very hard to measure a flow of ions with a current meter, unless you create extra ions with a source, like a spark or a radioactive source.

Air can be turned into a conductor by applying a voltage of > 1 Megavolt per meter. But then it sparks over, and the current is (momentarily) so high that it is very hard to measure.

Warnings:
  • Be very careful with radioactivity! A contained source of alpha particles will cause lots of ionisation, but won't get through your skin - but don't breathe or eat it!!!
  • Be very careful with high voltages (over 160V DC). By using plates very close together, you can create a strong electric field gradient, without using excessively high voltages.
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #7 on: 22/03/2015 00:18:40 »
To see how the charge on the electron was originally measured, see: newbielink:http://en.wikipedia.org/wiki/Oil_drop_experiment [nonactive]

Air is (mostly) an insulator, so it is very hard to measure a flow of ions with a current meter, unless you create extra ions with a source, like a spark or a radioactive source.

Air can be turned into a conductor by applying a voltage of > 1 Megavolt per meter. But then it sparks over, and the current is (momentarily) so high that it is very hard to measure.

Warnings:
  • Be very careful with high voltages (over 160V DC). By using plates very close together, you can create a strong electric field gradient, without using excessively high voltages.

Would there be another way to ionize the air first using high voltage and then create a negatively charged plate to accelerate these newly ionized molecules.
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #8 on: 22/03/2015 00:53:41 »
Would there be another way to ionize the air first using high voltage and then create a negatively charged plate to accelerate these newly ionized molecules.

Try looking up electrostatic dust precipitators, or electrostatic paint spraying. They're not exactly what you are looking for but might give you ideas.
 

Offline evan_au

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Re: Can an electromagnet repel ionized air molecules?
« Reply #9 on: 22/03/2015 06:20:36 »
You could try the Americium alpha-particle source from a smoke detector. Don't break the radioactive capsule open, as it also emits gamma rays, which will pass through your skin, and represents a cancer risk!

The next problem is to make the movement of the ions visible...
 
The current is very low, but the smoke detector has a sensitive circuit to detect any ionisation current in the air, and in a separate sealed cell. Smoke particles reduce the current, which is detected by the smoke alarm.

Millikan used tiny oil droplets to make the movement of the ions visible in a microscope.

A circuit of an IC-based smoke detector may be found here.
And a detector made out of a tin can.
« Last Edit: 22/03/2015 06:26:05 by evan_au »
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #10 on: 22/03/2015 07:12:53 »


would this work for accelerating and creating the ions. with the enamel on wire on the inside of the tube stripped to allow the current to flow freely through the air acting as an electrode.
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #11 on: 22/03/2015 08:05:50 »
would this work for accelerating and creating the ions. with the enamel on wire on the inside of the tube stripped to allow the current to flow freely through the air acting as an electrode.

The diagram is unclear, it seems to show the 2 plates (tubes?) connected together, this would short cct the voltage source.
Or is the wire from the -ve terminal suspended in the centre of the 'tube'? - if they are tubes, why 2 in this case?
Can you make this clearer please.
Why not use 2 flat plates?

As evan says, you need lots of volts. Something like a Wimshurst machine.
If you know what you are doing you could use an EHT generator from an old CRT monitor or TV, but only if you are experienced, they create dangerous voltages and sometimes X-rays.
Do they still sell electric air ionisers? That might provide useful parts, less dangerous, but still needs care?

Suggest you do some reading up 1st.

 
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #12 on: 22/03/2015 08:46:52 »
sorry about the unclear diagram the two tubes inside are meant to be flat metal plates and the second wire connecting from the negative terminal. I am doing research outside of this but i am using this to check my work before i start so i don't begin wasting my time. the two plates are meant to form a capacitor so that one end would be negatively charged which also connects with the wire which should ionize the air molecules causing them to repel away from the plate.
 

Offline evan_au

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Re: Can an electromagnet repel ionized air molecules?
« Reply #13 on: 22/03/2015 09:45:29 »
Quote from: starwarsmat
would this work for ... creating the ions.

The best way to ionise air is with a very sharp needle; this promotes corona discharge.
Very high electric field gradients occur at the sharp tip. You can reach the 1MV/m required for air ionisation with a DC voltage of 100V or so; put the negative end on the needle, and a flat plate for the positive.

If you look at high voltage power lines (where they wish to avoid corona discharge), you will see that they have removed all sharp points from conductors, and replaced them by rounded shapes.

But this doesn't explain how you will visualize the movement of the ions...
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #14 on: 22/03/2015 22:35:23 »
would the corona discharge ionize all the molecules in that region of the tube or only a certain percent? would changing the medium that is being ionized allow for increased visibility such as submerging the device in water or oil?
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #15 on: 23/03/2015 00:23:29 »
would changing the medium that is being ionized allow for increased visibility such as submerging the device in water or oil?
Not a good idea, especially water.
Won't help if air molecules are your target.
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #16 on: 23/03/2015 23:43:42 »
I thought that the water wouldn't work just wanted to make sure. If I have the metal plates in my diagram 1.27 cm apart and i have the electrode 1.27 cm away from the plate could the corona discharge damage the source of hv?
« Last Edit: 24/03/2015 07:02:46 by starwarsmat »
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #17 on: 24/03/2015 08:06:19 »
I thought that the water wouldn't work just wanted to make sure. If I have the metal plates in my diagram 1.27 cm apart and i have the electrode 1.27 cm away from the plate could the corona discharge damage the source of hv?
Normally you wouldn't let the corona arc over and in that situation you should be ok. If arcing occurs it will depends on your hv source (mm sounds like a condiment  :)) as there will be instantaneous currents that could cause insulation to break down.
Go slowly in turning up the wick and back off if you start to hear a crackling or change of tone of any hum, buzz etc.

 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #18 on: 29/03/2015 06:58:57 »
Thank you for your responses so far, they have been very helpful. Could I make a wimshurst machine to use as a consistent high voltage generator for this project or is there another high voltage from low voltage generator I could create.
« Last Edit: 29/03/2015 07:32:25 by starwarsmat »
 

Offline evan_au

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Re: Can an electromagnet repel ionized air molecules?
« Reply #19 on: 29/03/2015 10:47:27 »
Quote from: starwarsmat
is there another high voltage from low voltage generator I could create?
Since you want the electrons to move in a single direction, you want a high voltage DC source.

Old-fashioned TVs have a variety of high-voltage DC sources, from hundreds to thousands of volts. However, you need to have a good knowledge of electronics to repurpose these circuits. This sounds too dangerous for your level of experience.

Another kind of high-voltage DC source is a Van de Graaff generator. These can run off a wall socket, and generate high DC voltages. But be very careful - if you try to peer into the space between the positive and negative electrodes using a microscope, the shortest path for the spark may be between your ears!

So any experiments with high voltages are quite dangerous. It's probably better to use a low-current DC source of a hundred volts, and position the plates close together, rather than have a low-current DC source of thousands of volts and position the plates further apart.

But before you start building, determine how you are going to measure the speed of ions in the air. Individual ions are very small - in fact, invisible.

The Millikan experiment used a variable DC voltage to balance the attraction of the electric field against the force of gravity. So determine if you need a fixed or variable DC voltage. (Wimshurst and Van de Graaf generators do not produce a very stable voltage - and if it arcs over, the voltage must build up from zero again.)
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #20 on: 29/03/2015 20:53:54 »
I was hoping to get a large enough density of air molecules ionized that the movement of air would have an impact on other objects that could be used to determine their velocity. As for the voltage i was hoping to have a controllable voltage source that would allow me to see the differences the voltage has on the speed of the ions.
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #21 on: 30/03/2015 00:04:55 »
I was hoping to get a large enough density of air molecules ionized that the movement of air would have an impact on other objects that could be used to determine their velocity. As for the voltage i was hoping to have a controllable voltage source that would allow me to see the differences the voltage has on the speed of the ions.

What do you mean by other objects? They would have to be very light eg smoke particles, even then they would add mass to the air molecules and would have to be taken account of in any calculation.
Ion wind generators you can buy eg http://www.imagesco.com/kits/negative-ion-generator.html

Is this your objective?

 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #22 on: 30/03/2015 00:43:08 »
My goal is quite similar to that, but I was hoping to make one more powerful so that it could push for example a soccer ball. then test how much the voltage attached affects the force and to see if the device can be scaled up.
 

Offline Colin2B

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Re: Can an electromagnet repel ionized air molecules?
« Reply #23 on: 30/03/2015 10:17:45 »
My goal is quite similar to that, but I was hoping to make one more powerful so that it could push for example a soccer ball. then test how much the voltage attached affects the force and to see if the device can be scaled up.
I'd start with something really light- balloon?
Soccer ball will need a very large machine, would take a lot of resources, do you have a large research grant? I haven't done a calc on what it would take to move a ball, but I'm sure the power required will be outside your reach (even assuming it could be done).
Remember charge will build up on any object the ion stream is aimed at, also dust molecules will become charged and move towards areas where they can neutralise so you'll get lots of irritating effects eg dust build up on surfaces and static discharge.

You are talking about an application that will need a lot of EHT, this can be very dangerous. Read up on safety precautions. These voltages can break down insulation and tunnel through ( physically, not in quantum sense) insulation as an invisible hole, so what looks secure can be dangerous. The cable itself can act as a capacitor and cause flash over. Don't go near any live circuits. If you get a spark over into flesh it can look insignificant on the surface, but like a bullet wound, there is a lot more damage inside. Even when probing mains voltage ccts, keep one hand in your pocket so you don't accidentally touch earth + live & make a cct. Make sure your EHT generator is screened as many produce X-rays.

Be very careful.


« Last Edit: 30/03/2015 15:41:42 by Colin2B »
 

Offline starwarsmat

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Re: Can an electromagnet repel ionized air molecules?
« Reply #24 on: 31/03/2015 08:14:51 »
from the preliminary calculations i have done each atom ionized at the distance of the electrode assuming only one electron of charge is added to each molecule, a force of 8.896*10^-13 would act upon each molecule. if all air inside of the chamber is ionized and repelled how much force would be generated cumulatively when exiting. would adding multiple electrodes help increase the force as more molecules are ionized or would it cause some of the ions closer to the original electrode to be repelled backwards.
« Last Edit: 31/03/2015 08:50:51 by starwarsmat »
 

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