You can use these types of electromagnetics to cancel out a field within a small region, but a lot depends upon the shape of the field you are attempting to eliminate. I have seen Helmholtz coils used to balance out the earth's field in experiments. In this case the incident field is almost constant within the region needing cancellation. A strongly varying field would be very difficult to cancel.
Dave -----Original Message----- From: Daniel Rocha <[email protected]> To: John Milstone <[email protected]> Sent: Fri, Jul 26, 2013 12:54 pm Subject: Re: [Vo]:Defkalion/MFMP implications for electrolysis? Because of the above limitations of passive shielding, an alternative used with static or low-frequency fields is active shielding; using a field created by electromagnets to cancel out the ambient field within a volume.[7] Solenoids and Helmholtz coils are types of coils that can be used for this purpose. We saw a solenoid around the reactor, didn't we? https://en.wikipedia.org/wiki/Electromagnetic_shielding 2013/7/26 DJ Cravens <[email protected]> the magnetic field from a dipole falls of as the inverse cube of the distance. .... it falls off quickly. I am not sure what it would be outside a mu metal shielded device, but I would expect not much would be available for "tools across the room". Date: Fri, 26 Jul 2013 13:45:17 -0300 Subject: Re: [Vo]:Defkalion/MFMP implications for electrolysis? From: [email protected] To: [email protected] Also, this: https://en.wikipedia.org/wiki/Neodymium_magnet_toys 2013/7/26 Daniel Rocha <[email protected]> It is a strong field. But it falls fast, specially if the magnetized object is tiny: https://en.wikipedia.org/wiki/Neodymium_magnet 2013/7/26 Jones Beene <[email protected]> That kind of field at 20 cmfrom the device (their claim) would be pulling tools from across the room. Jones -- Daniel Rocha - RJ [email protected] -- Daniel Rocha - RJ [email protected] -- Daniel Rocha - RJ [email protected]
