A practical realization of this criterion is to minimize the time required to tip the spins by, say, 90 degrees, the so-called 90-degree pulse.These design goals are equivalent to maximizing theQ-factor, inductance, filling factor, etc., only for a simple solenoid that is full of the sample and is a part of a compact resonant circuit--the usual case for NMR/MRI. In the general case, one must use