Magnetic Induction Chambers

I don't really know the answers to your specific questions, but I can mention a few things:

1. One foot diameter by 2 feet long is a huge volume in which to create a magnetic field. You better plan on opening the packages and passing the beads through a much smaller volume. The tricky part will be keeping the beads in the desired orientation.

2. The galvanized ducting will be reducing the field, not strengthening it. Plan on using fiber or plastic.

3. Calculating the field strength inside a solenoid (coil of wire) is a standard first-year physics exercise. Look it up.

4. It only takes a fraction of a second to a few seconds to magnetize things. No need for hours or even minutes.

I'm a high school drop out so i didn't make it to physics, no prob;

thanks for the tips, yep, shrinking the diameter to 2 inches, it will take milliseconds, and going with PVC. The beads are on strands, so I'll angle the tube and slide 'em thru.

getting a bunch of solid 10 gauge copper wire, now the only question is to acheive the target gauss of 800-1000, what juice and how many winds on how many feet.

I'll see if i can find that calculation on the internet. was considering 24v @ 5amps to start, & get my winds and length from there.

thx again,

Jay

I'm away from home, but will return tomorrow, so I will be able to look up the solenoid formula if you haven't found it by late tomorrow.

With size 10 wire, you will probably want lower voltage, like one or two Volts. If you have any place that you can pick up an old spot-welding transformer and a high current diode, that would do the job well. The wire should be varnished, not plastic insulated, so the turns will be as close to each other as possible.

You didn't say how big the beads are. I'd recommend making the inside of the coil just large enough so a single strand of beads will fit inside.

Standard procedure would be: 1. Insert beads. 2. Pulse the current (turn it on and off). 3. Remove that set of beads. If the strand is longer than the coil, then move a little less than the length of the coil, and repulse.

Good Luck

Thanks for the tip.

Did find the calculation and other resources pertinent here: http://www.ndt-ed.org/EducationResources/CommunityCollege/MagParticle/Physics/CoilField.htm

Working with a welder repairer who referred me to this forum, will ask about the lower voltage. Would prefer a continuous application, as the strands we work with are up to 8ft long and up to 1.5 inches wide. Wanted to slide them thru.

Cheers & have a nice one!

Jay

Hi,

do you want to have a remanent magnetisation of the beads equivalent to 800G or do you want to have the 800G in your chamber?

If to magnetise the beads to a required value then you need the B-H curve, the flux-density versus field-strength curve of the material.

For your materials this will be available on the internet.

Then: it is much more difficult to change the direction of the magnetisation than to magnetise a demagnetised material up to a wanted value.

So depending on the requirement: how parallel to the axis is parallel in your sense?

Or: what is the primary requirement? Usually sufficient force. ?

If to be demagnetised: make a first coil with AC and continuous slow pass of the beads - same coil as for magnetisation.

If only to re-magnetise or change of field-direction make a circumferentially wound cylindrical coil.

Put this inside a steel (any type if DC) cylindrical tube with flat ringlike end-plates and an inner nonmagnetic (aluminum, brass, plastic, glass, wood) tube that eases the pass of the beads. Set the length 1.5 to 2 times the diameter of the inner tube.

If your coil has n windings with I amperes then n x I = H x L (L = length of distance between end-plates).

Switch over your thinking from Gauss and Oersted to Tesla and Amperes per meter, the SI-system.

10,000 Gauss is 1 Tesla = 1 V x s/m² , x = multiplication.

H is magnetic field strength, in nonmagnetic material with sufficient accuracy is valid: B=µ_oxH B=flux density (Tesla), H= field strength (a/m), µo= permeability of vacuum or 8.8x10^-6 Vs/Am.

If you aim at 0.1 T, or 11x10³A/m, and the length of the coils (between end-plates is 2.5cm or 1") then n x I = 11X10³x0.025A = 275 A.

So you can use 1 turn at 275 amperes or 100 turns at 2.75 amperes or any other relation that is convenient.

Next: calculate the resistive loss and adjust wire gauge and dimensions of coil.

Next: calculate cooling, water or air? or measure by known (low by low current) resistive loss the related temperature rise and scale up to needed value of current if the insulation will meet the temperature rise.

If not: improve cooling or make coil bigger by thicker wire.

If power loss is not acceptable: start pulse magnetising.

Have success!

RHABE

Thanks, a bunch to think about, but 'druther now than later when stuck!

Aloha,

Jay

Thanks for the input, the results were useful, but inapplicable at this time.

Next go out will have a lot more thought, and power! Need a welder or some such for the field I want, magnetic field generation in a tube is like herding fleas!