I'm trying to find out a method of creating a powerful electromagnetic field, cylandrical, about 3/4 m long.

The thing is, I don't want it to be a soleniod, that just won't work for what I'm trying to do.

The easiest way to explain it is like a lightsaber. I need for the light to be quite a strong electromagnetic field which will fit in the 'saber handle'. Forget about the power source, I just need something that'll work the way I want that realy isn't too complicated to make, and as I said needs to fit into the 'handle'.

Because it's an invention I'm working on, I can't givve any more of the specifics. Any help's apprediaated.

Perhaps if you could explain what this em field is required to do ( use an analogy that doesn't give details of your idea).
From your description, its difficult to understand what you want.

This thread exists in Physics & Math already. It should be locked.

Gabreal: making stable electromagnetic fields that have any effect on radiation/charged particle streams is a very difficult proposition. If you examine the Tokamak reactor (or any of the experimental fusion reactors) this may help to demonstrate the magnitude of the problem.

The magnets required to contain the fusion reaction in these devices weigh hundreds of tons, and still are barely strong enough to do the job. (Thus far, none of the reactors has had any net power gain that I know of.) There are several light saber threads in Sciforums where alternatives were discussed.

For some simple science:

An electromagnet is made by running current through a wire. ALL wires with current running through them are electromagnets. If I recall correctly, the magnetic "lines of force" spiral around the wire; if we consider a circuit where current travels from negative to positive (which I believe it generally does, heh) then the spiral around the wire would be counterclockwise if you were looking in the direction the current travels. (This is my extremely crooked explanation of the left-hand rule and may be incorrect - I'm a programmer, not an engineer.)

Now, by wrapping said wire around a piece of iron, like a nail, one can turn the nail into an electromagnet which has the properties of a regular bar magnet. If I understand correctly, this is because making the wire into a spiral orients the (sub)spiral lines of force around the wire so that they all go in relatively the same direction. Changing the tightness of the windings changes the force of the magnet, I believe.

Check this out:
http://www.christian81.free-online.co.uk/4experiment2.1.htm

This is a simple nail/wire/battery electromagnet, with some extra unnecessary apparatus to make it look official.

Now, if I remember right, magnetic lines of force do not cross, but simply run up against each other like lines on a topological map. As such, I have never figured out one of the main problems with the Light Saber concept, which is:

How do you create a cylindrical electromagnetic field with only one magnet? It's easier to imagine how you might create it within a cylindrical magnetic chamber (although it turns out that this too is hard), but with just one magnet or ring of magnets, I'm really not sure how you make a closed-ended tube of arbitrary length.

For this reason, in the previous light saber threads on Sciforums, we generally discussed other apparatus that might have similar effects, such as Arc blades, heat blades, beam cutters, and so on. I'll try to find the previous thread if I can.

Here ya go - it's

http://www.sciforums.com/showthread.php?t=12662

there may be others but this is the one I contributed to. Hope it helps - it's a lot of reading and a lot of fantastic (as in not very real) theorizing.

EDIT:

Sorry, it's actually

http://www.sciforums.com/showthread.php?s=&threadid=28834

I bought mine at a local party store.

Gabreal - was this for a propulsion system? I saw some of your other posts and thought I might have it wrong. Assumption = my bad.

Look here for a laugh - solenoid example

http://webphysics.davidson.edu/Applets/BField/Solenoid.html

Sorry for not postung for a while,
BigBlueHead, yes, it is actually for a propulsion device, the lightsabre thing was just to help explain what I need for the propulsion system.

I've researched solenoids, but they don't give me what I need. It has to be something like this:
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power source/ electromagnetic field
device

Any ideas?

I guess you could run a length of wire as a loop (but with the shape you want) with some DC setup and create a circular B field around the wire loop. That is the only way I can think of that can create a field that extends like that without increasing the loop field's size (as long as you keep the power down). Trouble is you have wires extending from your power source. I don't think you can direct electromagnetic fields in the way you want.

Hmm... I should mention at this point that my background in physics is very weak... anyway, some questions:

Is this field just meant to contain something, or does it need to accelerate it as well?

How far does the field need to extend away from the projector (out into the open air or whatever)? At any real distance the inverse square law starts to bite you pretty hard.

Given what we know about electromagnetic fields, if we assume that substances conform to the curvature of the lines of force, it's difficult for me to imagine a containment field that relies on attraction (to the lines of force) because whatever was being contained would necessarily run up against the magnet. Has to be repulsion... but magnetic repulsion is dispersive, so I'm unsure how to create a "shell" using only repulsive force from a single remote source.

Gabreal:


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Isn't that a dildo?


Now, its been a year or so since I've been taught my physics and trust me- shut me right up so I can't say I'm an expert in this field, however fascinating.

I'm thinking of toroids- you want a strong elecromagnetic field, yes?
From my understanding, the tighter you make a rod wound with insulated wire into a coil, the more concentrated the electromagnetic field in the center (the premise for superconducters).

Is it a)stupid or b)impossible to gather toroids together in the shape of a lightsaber? Something like a stack of tires. You run a current through it (you yourself said the power source was inconsequential for now so we can throw the problem of how out the window) and with the electric field lines gathered in the center- the number of lines are proportional to the strenght of the field, more lines more power.

Yes? No? Maybe so?

Bigblue:
Given what we know about electromagnetic fields, if we assume that substances conform to the curvature of the lines of force, it's difficult for me to imagine a containment field that relies on attraction (to the lines of force) because whatever was being contained would necessarily run up against the magnet. Has to be repulsion... but magnetic repulsion is dispersive, so I'm unsure how to create a "shell" using only repulsive force from a single remote source.
Call me out as stupid schoolgirl- but won't the stacking up of toroids (if possible) take care of the containment problem?

Only if you're willing to have the field entirely contained within the magnets. The idea here (I think) is to have the field somewhat remote from the magnets creating it - a sort of "base station" series of coils with a cylindrical field that sticks out from there. But, we'll need a second from gabreal, since it's her/his idea and I'm just guessing from descriptions/diagrams.

That's why I'm not sure of a good answer.

Then that's insane- you cannot mold electromagnetism unless you contain it within the very thing emmanating it. Only thing in mind otherwise is a sheat of antimatter to fit over the force shooting out from the base like an invisible condom, which is ridiculous.

Yes. I think I see it. Slip the condom over the dildo. That would prevent the force from shooting out all over the place and making a right mess.

I like the conceptualization. Quite impressive

the damn picture thing went wrong. Meh...

BigBlueHead's got it right, I want an electromagnetic field, around 75cm long, without requiring wire in that space. If it's impossible, I'll just change the design. Ah well, I'll just change the design.

While the subject of lightsaber construction was proposed earlier, I wanna share my design. Tell me what's wron with it...

In the handle there is something like a 5 volt battery connected to a taser's circuitry amplification thing, which is then connected to another amplification thing, then to another. I remember somebody said to me that by doing this you can get around 20,000,000,000 volts. It'd have to be coated with something like liquid nitrogen, so that the circuitry doesn't melt away.

Concealed in the handle is a pole with wire wrapped around it. The wire is connected to the second amplification thingy, giving it a powerful electromagnetic field. The third one is connected to a ring of metal with a hole in the centre, where the pole comes out of the handle

When power is supplied, plasma is created by the 20,000,000,000 volts, and is contained in the electromagnetic field. The plasma should, to the best of my knowldge, cut through anything beause of how hot it is. Then again, that's just to thebestof my knowledge.

Whatcha' think?

Um...just to let you know that if you just 5 volts all the way to 20,000,000,000 (are you sure this souldn't be 20,000?) you decrease the current dramatically. Use:

Voltage = Current * Resistence or just V=IR

I got the figures from some guy on the net a while ago. The circuitry amplifying thing in a taser turns 5 volts to a 100,000, I know that. The guy said that it then brings it to something like 5,000,000, then to 20,000,000,000 with a third circuitry amplifying thingy.

Of course I have no idea what thateqation means. Please elaborate.

It is Ohm's law.

But I was a bit mistaken. The circuitry for a stun gun that the guy gave you includes transformers that take the voltage and increase it at the expense of current available. So as the voltage is increased, current drops lower and lower.

Your drawing me in.

I'm still not quite sure what you mean. What do you mean by 'So as the voltage is increased, current drops lower and lower'

Do you know what the end voltage would be?

It can be whatever you want it to be with the right circuitry. Stun guns use a series of transformers to take the relatively low 9 volt input from a battery, turns it into an oscillating current (AC) and jumps it up to 100,000 in some examples of stun products. And in doing so the current drops dramatically as to not kill someone when it is used. A transformer can step up or step down voltage but at a loss or gain of current and visa versa.

Hence the energy is always the same... but will twenty billion volts really have much of an effect at the miniscule amperage this would produce? I know the voltage determines (to some extent) the ionization potential; I remember hearing once that electricity requires ~32,000V to arc through an inch of air.

However, if you really had something that produced 20,000,000,000V, it would be able to arc about 9 miles by that calculation; in practice, it wouldn't go nearly that far, since it would generally arc to a drain, power outlet, or other ground terminal. That would look pretty weird.

I'm really sorry, but I'm still not sure what you mean by loss of current.
Please use laymens terms.

Before you go any further I think you need to read some electronics resources. Those will help immensely.

As BigBlue said, when you step up the voltage of a system without using any sort of amplifier something else has to give...remember energy is neither created nor destroyed. So if you want to use stun gun circuitry, which will take a small DC source, oscillate it, and step up the voltage with multiple transformers something has to give in the process....remember energy is neither created nor destoryed. The power output of the stun gun will always be the same and that power output won't increase without some sort of outside influence to the system. So if voltage and current are responsible for the amount of power output and power output is to stay the same, then either voltage or current much change in response. So if you are changing the voltage to an incredibly high number like 20,000,000 volts, then the current will drop considerably. That is why stun guns don't kill people when used properly. The current is far to low to stop a person's heart.

What does this mean to you? I don't know. Because none of use know what you are trying to do other then some sort of propulsion method. Not to discourage you but given your lack of electronics knowledge or physics for that matter, your goals could be harder than you think. My advice? Use all the wonderful web resources out there that go into detail about electricity, physics and magnetic fields. I'm sure you'll pick up a lot.

Blackholesun: I thought current was what caused burns from electrical shock; I think a sustained DC arc through your heart will still kill you if it lasts long enough, even with very small current.

Often what kills people with electrical shocks is getting a shock that travels from one hand to the other and hence through their heart - the tissues get burned by the current and the damage to the heart is too great. This happened to a teacher of mine in HS - said he was holding a power tool when he touched a lightswitch, and the tool was live. He had to get an artificial valve in his heart afterward.

Ok I did jump the gun there. You're right. The low current is not so much to not KILL a person but to prevent external and internal burns when used properly (I'm guessing holding one on someone for a couple of minutes would be misuse lol). My bad.

BlackHoleSun, thanks for the help, same to BigBlueHead, I really apreciate it.

Okay, so you're saying that taseres don't kill people because the current is being converted to volts, right? So does this mean that the current only goes a certain distance, or that the current it small, because it has been converted into more volts?

I wanna make sure I've got the facts straight.

BlackHoleSun, thanks for the help, same to BigBlueHead, I really apreciate it.

Okay, so you're saying that taseres don't kill people because the current is being converted to volts, right? So does this mean that the current only goes a certain distance, or that the current it small, because it has been converted into more volts?

I wanna make sure I've got the facts straight.


You're not turning anything into anything else. What you are doing is not violating conservation of energy. There is a specific power output to any device. If it is a closed system you can't change the power output unless with any outside power source. So if power is expressed as voltage times current and power stays the same then if you want very high voltage then current drops during the voltage increase. One way is done with a transformer. You can reverse the process and get a lot of current if you give up how much voltage you need. As Blue said a stun gun is designed with low current in mind to prevent burns. The current flow is following the path of least resistance or most likely through one electrode, through the skin it touches, and back into the other electrode the completes the circuit. That is unless you give it a better path of even less resistence.

Okay, so you're saying that taseres don't kill people because the current is being converted to volts, right? So does this mean that the current only goes a certain distance, or that the current it small, because it has been converted into more volts?

Electrical arcs through the body (basically) have two effects.

1) Electrical stimulation of nerves/muscles. Electricity acts upon your nerves, causing them to fire (or cascade or whatever - I'm not a neurologist). This is true for muscular nerves, but also for others - if you test a battery on your tongue (don't try this) you'll briefly notice an awful taste, which is not what the battery tastes like. This (I think) is direct stimulation of the tongue's nerves by the electricity.

This effect is stronger when the voltage is stronger. A sufficiently high-voltage shock will stop your heart by neural stimulation.

BUT - bear in mind that as long as there is no arcing, your body is sufficiently conductive to allow voltage to travel through it. This is the trick they use with Van De Graff generators, and even a modest one will send fifty thousand volts through your body without injuring you.

2) Burns. Electricity, when it travels through most materials, loses some of its energy to heat - this is how an electric stove works. High amperage (current is measured in amps) tends to produce more heat this way than low current. Normally, death from electrocution is from burns to your internal muscles and organs, particularly your heart.

Generally the current is the more important part of the equation - fifty thousand volts won't kill you at .001 amps, but 100 volts at 1 amp will probably kill you.

EDIT: looking back at your question, I should mention that, for electricity to harm you, your body has to form part of a circuit with the source. That is, the electricity has to be able to go from the source, all the way through some part of you, and reach a ground, like a drain pipe or electrical outlet.

Electricity can't go halfway through you. In the case of the stunguns, it travels through a small half-circular path inside your body.