scholarly journals Cluster observations of ULF waves with pulsating electron beams above the high latitude dusk-side auroral region

2004 ◽  
Vol 31 (5) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Morooka ◽  
M. André ◽  
J.-E. Wahlund ◽  
S. C. Buchert ◽  
A. N. Fazakerley ◽  
...  
Keyword(s):  
High Latitude ◽  
Electron Beams ◽  
Ulf Waves ◽  
Auroral Region

scholarly journals Long-Lasting Poloidal ULF Waves Observed by Multiple Satellites and High-Latitude SuperDARN Radars

2018 ◽  
Vol 123 (10) ◽  
pp. 8422-8438 ◽  
Author(s):  
X. Shi ◽  
J. B. H. Baker ◽  
J. M. Ruohoniemi ◽  
M. D. Hartinger ◽  
K. R. Murphy ◽  
...  
Keyword(s):  
High Latitude ◽  
Ulf Waves

scholarly journals High-latitude observations of ULF waves with large azimuthal wavenumbers

2000 ◽  
Vol 105 (A3) ◽  
pp. 5453-5462 ◽  
Author(s):  
T. K. Yeoman ◽  
D. M. Wright ◽  
P. J. Chapman ◽  
A. B. Stockton-Chalk
Keyword(s):  
High Latitude ◽  
Ulf Waves

scholarly journals High-latitude HF Doppler observations of ULF waves: 2. Waves with small spatial scale sizes

1999 ◽  
Vol 17 (7) ◽  
pp. 868-876 ◽  
Author(s):  
D. M. Wright ◽  
T. K. Yeoman
Keyword(s):  
High Latitude ◽  
Radar Data ◽  
Mhd Waves ◽  
Ulf Waves ◽  
Vhf Radar ◽  
Magnetic Signature ◽  
High Latitude Ionosphere ◽  
Field Lines ◽  
Ground Magnetic ◽  
The Waves

Abstract. The DOPE (Doppler Pulsation Experiment) HF Doppler sounder located near Tromsø, Norway (geographic: 69.6°N 19.2°E; L = 6.3) is deployed to observe signatures, in the high-latitude ionosphere, of magnetospheric ULF waves. A type of wave has been identified which exhibits no simultaneous ground magnetic signature. They can be subdivided into two classes which occur in the dawn and dusk local time sectors respectively. They generally have frequencies greater than the resonance fundamentals of local field lines. It is suggested that these may be the signatures of high-m ULF waves where the ground magnetic signature has been strongly attenuated as a result of the scale size of the waves. The dawn population demonstrate similarities to a type of magnetospheric wave known as giant (Pg) pulsations which tend to be resonant at higher harmonics on magnetic field lines. In contrast, the waves occurring in the dusk sector are believed to be related to the storm-time Pc5s previously reported in VHF radar data. Dst measurements support these observations by indicating that the dawn and dusk classes of waves occur respectively during geomagnetically quiet and more active intervals.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions) · Magnetospheric physics (MHD waves and instabilities)

Extremely Collimated Electron Beams in the High Latitude Magnetosphere Observed by Arase

2021 ◽  
Vol 48 (5) ◽  
Author(s):  
Y. Kazama ◽  
H. Kojima ◽  
Y. Miyoshi ◽  
Y. Kasahara ◽  
S. Kasahara ◽  
...  
Keyword(s):  
High Latitude ◽  
Electron Beams

scholarly journals High-latitude HF Doppler observations of ULF waves. 1. Waves with large spatial scale sizes

1997 ◽  
Vol 15 (12) ◽  
pp. 1548-1556 ◽  
Author(s):  
D. M. Wright ◽  
T. K. Yeoman ◽  
P. J. Chapman
Keyword(s):  
Field Line ◽  
High Latitude ◽  
Vertical Component ◽  
Low Frequency ◽  
Mhd Waves ◽  
Ulf Waves ◽  
Large Spatial Scale ◽  
Field Line Resonances ◽  
Doppler Data ◽  
Magnetometer Data

Abstract. A quantitative study of observations of the ionospheric signatures of magnetospheric ultra low frequency (ULF) waves by a high-latitude (geographic: 69.6°N 19.2°E) high-frequency Doppler sounder has been undertaken. The signatures, which are clearly correlated with pulsations in ground magnetometer data, exhibit periods in the range 100–400 s and have azimuthal wave numbers in the range 3–8. They are interpreted here as local field line resonances. Phase information provided by O- and X-mode Doppler data support the view that these are associated with field line resonances having large azimuthal scale sizes. The relative phases and amplitudes of the signatures in the Doppler and ground magnetometer data are compared with a model for the generation of Doppler signatures from incident ULF waves. The outcome suggests that the dominant mechanism involved in producing the Doppler signature is the vertical component of an E × B bulk motion of the local plasma caused by the electric field perturbation of the ULF wave.Key words. Auroral ionosphere · Magnetosphere-ionosphere interactions · MHD waves and instabilities HF Doppler · ULF Waves

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

Sign in / Sign up

Export Citation Format

Share Document