For 10 points, name this value that describes the measure of a magnetic dipole's ability to turn in the presence of an applied magnetic field.
It is adiabatically invariant for plasma, which is an important fact in the analysis of plasma mirrors.  At an atomic level it is quantized, meaning that it may be oriented only at certain discrete angles relative to an applied field.  For a current loop it is proportional to the current times the size of the enclosed area and is usually expressed in amperes per square meter.  For 10 points, name this value that describes the measure of a magnetic dipole's ability to turn in the presence of an applied magnetic field.
It is adiabatically invariant for plasma, which is an important fact in the analysis of plasma mirrors.  
Magnetic dipole Moment