ASTM A848 (soft iron) core when exposed to overlaping magnetic fields

[WalkerYYJ]

Hi all,

I have an application where I need to produce linear motion between two overlapping DC solenoids (a large outer solenoid, and a small inner solenoid.)
In the interest of maximizing forces I would like to core the smaller inner solenoid with soft iron. For obvious reasons the larger outer solenoid must remain core-less (air core.)

No forgive me as its been a long time since I studied magnetism however:
My concern is what will happen to the magnetic domains of the iron core when placed inside of two diametrically opposed fields? If we feed the same amount of current to both coils will the core boost the power of the smaller coil which is in closer proximity, or will the presence of the larger coil produce some sort of hodgepodge of a magnetic filed resulting in large scale efficiency loss?


thanks!

 

[MagBen]

The maximizing force will occur when the inner solenoid with iron core is applied current, and then you apply an opposite field to the outer coil.
The min force occurs when you apply current simultanely since the iron core "see" a smallest field: H (inner) -H (outer). Assuming same ampere turns, the magnetization direction of iron core will be the same as the inner solenoid.

The base line is that the iron core only boosts the magnetic field at the same direction as its DOM (direction of magnetization). DOM is determined by combining effect of inner and outer coils.