The perpendicular scale of electron phase-space holes is investigated using electric field data from the Polar Plasma Wave Instrument. We show that the electron phase-space holes are roughly spherical for Ωe/ωp > 1, and become more oblate (with the perpendicular scale larger than the parallel scale) with decreasing Ωe/ωp. A scaling argument based upon electron gyrokinetic theory is proposed as a possible explanation for the observed scaling. The data indicate that the ratio of the parallel dimension (L∥) to the perpendicular dimension (L⟂) is such that L∥/L⟂ ≃ (1 + ρe²/λD²)−1/2. Our results provide a connection between the Geotail measurements in the deep magnetotail, where Ωe/ωp ≪ 1, and the FAST measurements in the low altitude auroral zone, where Ωe/ωp ≫ 1.
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