A Brief Primer on Adiabatic Pulses
Adiabatic Pulses Adiabatic pulses are a special category of pulses where both the amplitude and frequency (hence phase) of the pulses are modulated. They are designed to be insensitive to B1 inhomogeneities and miscalibrations, as long as the amplitude is above a certain threshold. They are ideal for uniform inversion or refocusing across large bandwidths. For more on adiabatic pulses, please refer to Chapter 5 in Ref. [1] and Chapter 12 in Ref. [2]. Some of these pulses have specific requirements that need to be met for them to behave ideally. In this section, we will discuss a few different types of adiabatic pulses and the ideal parameters needed for their optimal behavior. The Adiabatic Condition Adiabatic pulses need to satisfy the ‘adiabatic condition’ in order to achieve efficient inversion. The adiabatic condition is met when the effective B1 field is sufficiently larger than the rate of frequency sweep. That is, if the sweep is slow enough, the magnetization gets ‘dragged’ alo...