How Do Neodymium Cores Affect Solenoid Power and Efficiency?

[shy_barbarian]

Hi all, I've a few quick questions about solenoids, just want to understand things better.

As I understand it, the way a solenoid works is the iron core is sucked into the middle of the coil because this is where the coil achieves the highest inductance possible. Makes sense.
Incidentally, solenoids have a rather short throw, unless you use a very large coil.

2 questions:
1. I did a google search for neodymium solenoids and came up with nothing. I am guessing then that constructing an electromagnet with it's own permanent iron core, and then using a neodymium slug would not yield any more powerful results than a conventional solenoid would. Am I right? Why is this?

2. What are my options for creating a "long throw" solenoid? Obviously one option is using a very large coil. Another option as I see it would be to create a rod with permanent magnets placed at specific intervals, and use a series of "push-pull" electromagnets to propel the rod through them, similar in concept to a coil gun.

I didn't want to muck up another electromagnetic thread I have going with all these related but unrelated solenoid questions so I created another thread here.

Thanks!

 

[mfb]

1. I did a google search for neodymium solenoids and came up with nothing. I am guessing then that constructing an electromagnet with it's own permanent iron core, and then using a neodymium slug would not yield any more powerful results than a conventional solenoid would. Am I right? Why is this?

You cannot switch it off. If your electromagnet is stronger than the permanent magnet, you don't need the permanent magnet. And if it is weaker, you can ignore the electromagnet.

2. What are my options for creating a "long throw" solenoid? Obviously one option is using a very large coil. Another option as I see it would be to create a rod with permanent magnets placed at specific intervals, and use a series of "push-pull" electromagnets to propel the rod through them, similar in concept to a coil gun.

Looks like a good approach.