does anyone happen to know the amount of energy that would be required to suspend a plasma in an electromagnetic field. i know it can be done because plasma is an ionized gas but how much are we talking about.
That's a pretty broad question. Kind of like asking, "how long as a stick?". At the most basic level, the amount of force needed to restrain a plasma is entirely dependent on the amount of force the plasma is exerting to escape.
One of the factors in question is the ratio between amount of plasma and the volume of space in which it is being contained. Plasmasize 1 mg of hydrogen, and place it inside a magnetic container the size of a sports Arena, and the containment field does not have to be very strong at all. On the other hand, pinched plasma fusion reactors (like TokaMac) attempt to squeeze much more plasma into a much smaller space, and they require magnets with more crushing force than the hydraulic press at the junkyard.
I suppose the important thing is, the more you squeeze a plasma do more energetic it becomes and therefore, the more force it exerts to expand. To contain the plasma, your magnets must apply as much force as this "expanding force".