Properties of small-amplitude electron phase-space holes observed by Polar

We present Polar Plasma Wave Instrument (PWI) measurements of electrostatic solitary waves in the high‐altitude polar magnetosphere. These waves are electrostatic pulses that move parallel (and antiparallel) to the geomagnetic field and are similar to waves detected in many regions of the magnetosphere by other spacecraft. The PWI instantaneous dynamic range was 72 dB with an added 30 dB obtained by changing gain states. This large dynamic range enables the study of amplitude‐size relations up to a maximum electric field of 44 mV/m in the lowest gain state as well as enabling the investigation of small‐amplitude waves (