Whistler‐mode radiation from the Spacelab 2 electron beam

Abstract

During the Spacelab 2 mission the Plasma Diagnostics Package (PDP) performed a fly‐around of the shuttle at distances of up to 300 meters while an electron beam was being ejected from the shuttle. We discuss a magnetic conjunction of the shuttle and the PDP while the electron gun was operating in a steady (DC) mode. During this conjunction, the PDP detected a clear funnel‐shaped emission that is believed to be caused by whistler‐mode emission from the beam. Ray‐path calculations show that the shape of the funnel can be accounted for by whistler‐mode waves propagating near the resonance cone. Because the beam and waves are propagating in the same direction, the radiation must be produced by a Landau, ω/k∥ = vb, interaction with the beam. Other types of waves generated by the beam are also described.

Narrowband Z‐mode emissions interior to Saturn's plasma torus

“…Specifically, the electrostatic whistler emissions are propagating with wave normals on the resonance cone. The resonance cone angle, Ψ, is defined as [Gurnett et al, 1986;Farrell et al, 1988] …”

A Compact Loop Antenna System for Monitoring Local Electromagnetic Environments in Geospace

“…In the present study, we have developed a compact loop antenna system to be installed in an MSEE node, to detect magnetic vector fields. Its target frequency range is from ELF (hundreds of Hz) to MF (hundreds of kHz), corresponding to the plasma wave turbulence observed in the vicinity of the space shuttle in the ionosphere [3], [4]. The performance of the loop antenna system is confirmed to be sufficiently high to render it capable of measuring magnetic fields associated with plasma wave turbulence around space structures, in addition to intense natural plasma waves in geospace.…”

“…The measured sensitivities were 2 pT/Hz 1/2 , 200 fT/Hz 1/2 and 20 fT/Hz 1/2 at 1 kHz, 10 kHz and 100 kHz, respectively. The thick solid black line in the figure is the magnetic field intensity of a whistler-mode wave actually observed in the shuttle experiment [4], which would be detectable by our loop antenna system above 500 Hz. The rectangular regions represent typical magnetic field intensities of natural plasma waves in the magnetosphere: electromagnetic ion cyclotron waves (EMIC), magnetic noise bursts (MNB) and chorus emissions (for details, see for example [5]).…”

“…At ionospheric altitudes of a few hundred kilometers, the electron cyclotron frequency is of the order of 1 MHz, below which whistler-mode waves with large magnetic field components are excited and propagate. In fact, strong electromagnetic whistler-mode emissions with frequencies of up to about 1 MHz were generated by an electron beam emitted from the space shuttle, and were observed within several hundred meters of the shuttle [4]. Three loop antennas are arranged orthogonally, and enclose the MSEE body as shown in Fig.…”

“…This sensor network is designed to monitor electromagnetic activity simultaneously at multiple points in the vicinity (within km) of space plasmas. For instance, plasma wave turbulence was found to be generated in a region of several hundred meters surrounding the space shuttle, where both electrostatic and electromagnetic waves were observed [3], [4]. Knowledge concerning the structure of such turbulence is crucial for understanding the plasma dynamics around artificial structures, particularly in a space environment.…”