On the perpendicular scale of electron phase-space holes

• Published in: Geophysical research letters Vol. 27; no. 2; pp. 169 - 172
• Main Authors: Franz, J. R., Kintner, P. M., Seyler, C. E., Pickett, J. S., Scudder, J. D.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 15.01.2000; American Geophysical Union
• Subjects: Earth, ocean, space; Electric fields; Exact sciences and technology; External geophysics; Physics of the magnetosphere; Kinetic model; Satellite observation; Magnetospheric tail; Electric field; Phase space; Electrons
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/1999GL010733

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.