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[femm] Re: magnetic launcher




Very interesting idea, Hope my son like it so that I can justify and happily involve in his next science project.


Regarding the previous note from David about extending the capability of Femm for other applications. In the magnetic recording industry, FEM modeling is used to design reader (resistance change due to flux variation) & inductive writer. Also there are some efforts in the area micromagnetics (with grain boundary & exchange couple) and thermal effect (NiFe, a common MR material is also a good thermal gage). I am very pleased with femm and have high respect with David's one man single handed effort. Please let us know how can we help. I will glad to be part of the team.

James

From: mathewsd@xxxxxxxxxxxxx
Reply-To: femm@xxxxxxxxxxx
To: femm@xxxxxxxxxxx
Subject: [femm] Re: magnetic launcher
Date: Wed, 01 Dec 1999 10:25:01 -0800

If you are going to levitate something, Maglifter may be the way to go.
If you are going to shoot something, say to the moon, you need a
railgun or one of its variants. You should use railgun (or rail gun)
as a keyword in searching for information. Maxwell Laboratories in San
Diego builds these. The university at Austin, Texas (U. of Texas?,
Texas Tech?) is very active in this area. The way a railgun works is
this: A conducting loop wants to expand the area it encloses when you
pass a direct current through it, so you hold two sides (rails, coat
hangers, etc.) fixed and use your metallic projectile as a
freely-moving end piece. You start your projectile (paper clip) near
one end, let it pick up speed as it goes along the rails, and have it
go off the far end. When you hook your dc source at the near end,
i.e. near the starting point, the "loop" expands and sends the
projectile flying. Since dc power supplies don't like to see short
circuits, you actually charge up a big capacitor and attach it through
a small resistor to the rails. Yes, you can build a coil version, but
rails are better mechanically when large forces are involved.


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