scholarly journals Implications of unusual pitch-angle distributions observed by ISEE-1 and 2

2006 ◽  
Vol 24 (11) ◽  
pp. 3099-3113 ◽  
Author(s):  
C. A. Zuluaga ◽  
E. S. Beiser ◽  
J. Chen ◽  
T. A. Fritz
Keyword(s):  
Charged Particle ◽  
High Latitude ◽  
Pitch Angle ◽  
Angular Resolution ◽  
Radial Distance ◽  
Local Magnetic Field ◽  
Particle Source ◽  
Small Pitch ◽  
Short Period ◽  
Geosynchronous Satellites

Abstract. Unusual energetic particle pitch angle distributions (PADs) were observed by the ISEE-1 and 2 satellites at 3 h MLT and a radial distance of about 10–15 RE during the time period of 07:00-14:00 UT on 3 March 1979. The ISEE-1 satellite obtained complete 3-D distributions of energetic proton and electron fluxes as a function of energy, while ISEE-2 was configured to provide higher time resolution but less angular resolution than ISEE-1. The ISEE-1 observed a butterfly PAD (a minimum in the 90° PA particle flux) for a period of about 2 h (10:00–12:00 UT) for the electrons, and 3 h (09:00–12:00 UT) for the protons over an energy range of 22.5–189 keV (E1–E4) for the electrons and 24–142 keV (P1–P4) for the protons. The small pitch angle (15°, 30°) charged particles (electrons and protons) are seen to behave collectively in all four energy ranges. The relative differences in electron fluxes between 15° PA and 90° PA are more significant for higher energy channels during the butterfly PAD period. Three different types of electron PADs (butterfly, isotropic, and peaked-at-90°) were observed at the same location and time as a function of energy for a short period of time before 10:00 UT. Electron butterfly distributions were also observed by the ISEE-2 for about 1.5 h over 28–62 keV (E2–E4), although less well resolved than ISEE-1. Unlike the ISEE-1, no butterfly distributions were resolved in the ISEE-2 proton PADs due to less angular resolution. The measured drift effects by ISEE-1 suggest that the detected protons were much closer to the particle source than the electrons along their trajectories, and thus ruled out a nightside source within 18:00 MLT to 03:00 MLT. Compared to 07:30 UT, the charged particle fluxes measured by ISEE-1 were enhanced by up to three orders of magnitude during the period 08:30–12:00 UT. From 09:10:00 UT to 11:50 UT, the geomagnetic conditions were quiet (AE<100 nT), the LANL geosynchronous satellites observed no substorms, and the local magnetic field measured by ISEE-1 was almost constant, while the small PA charged particle (both electron and proton) fluxes measured by ISEE-1 increased gradually, which implies a particle source other than the substorm source. Based on detailed particle trajectory tracings in a realistic geomagnetic field model, the 50–200 keV protons with small PA at 10:00 UT ISEE-1 location on 3 March 1979 were passing through the northern high-altitude and high-latitude morningside region where the cusp should be located under a dawnward IMF component condition, while those protons with large PA may connect to the high-latitude morningside magnetopause. It is possible that the cusp source is responsible for the all particles observed during the event.

Pattern generation and motion control of a vortex-like paramagnetic nanoparticle swarm

2018 ◽  
Vol 37 (8) ◽  
pp. 912-930 ◽  
Author(s):  
Jiangfan Yu ◽  
Lidong Yang ◽  
Li Zhang
Keyword(s):  
Magnetic Field ◽  
Targeted Delivery ◽  
Pitch Angle ◽  
Dynamic Equilibrium ◽  
Equilibrium Structure ◽  
Pattern Generation ◽  
Analytical Models ◽  
Generation Process ◽  
Rotating Magnetic Fields ◽  
Small Pitch

Controlling a swarm of microrobots with external fields is one of the major challenges for untethered microrobots. In this work, we present a new method to generate a vortex-like paramagnetic nanoparticle swarm (VPNS) from dispersed nanoparticles with a diameter of 500 nm, using rotating magnetic fields. The VPNS exhibits a dynamic-equilibrium structure, in which the nanoparticles perform synchronized motions. The mechanisms of the pattern-generation process are analyzed, simulated, and validated by experiments. By tuning the rotating frequency of the input magnetic field, the pattern of a VPNS changes accordingly. Analytical models for estimating the areal change of the pattern are proposed, and they have good agreement with the experimental data. Moreover, reversible merging and splitting of vortex-like swarms are demonstrated and investigated. Serving as a mobile robotic end-effector, a VPNS is capable of making locomotion by tuning the pitch angle of the actuating rotating field. With a small pitch angle, e.g. 2°, the whole swarm moves as an entity, and the shape of the pattern remains intact. In addition, the trapping forces of VPNSs are verified, showing the critical input parameters of the magnetic field that affect the morphology of the swarm. Finally, we demonstrate that VPNSs pass through curved and branched channels with high positioning precision, and the access rates for targeted delivery are over 90%, which are significantly higher than those in the cases of particle swarms moving with tumbling motions.

Short helical antenna with extremely small pitch angle

2006 ◽  
Vol 49 (1) ◽  
pp. 17-19
Author(s):  
Ze-Hai Wu ◽  
Edward K. N. Yung
Keyword(s):  
Pitch Angle ◽  
Helical Antenna ◽  
Small Pitch

scholarly journals Nonlinear Effects and the Limitation of Electron Streaming Instabilities in Astrophysics

1985 ◽  
Vol 107 ◽  
pp. 355-359
Author(s):  
Steven R. Spangler ◽  
James P. Sheerin
Keyword(s):  
Charged Particle ◽  
Time Scales ◽  
Time Scale ◽  
Pitch Angle ◽  
Radio Galaxy ◽  
Linear Time ◽  
Nonlinear Effects ◽  
Particle Beam ◽  
Charged Particle Beam ◽  
Hydromagnetic Waves

Nonlinear effects, such as soliton collapse, will result in evolution of hydromagnetic waves excited by a field-aligned charged particle beam. If the time scale for such evolution is comparable to, or shorter than, linear time scales such as those for wave growth or pitch angle isotropization, then nonlinear effects may limit the instability. For conditions appropriate to relativistic electron streaming in a radio galaxy, the nonlinear time scale may be comparable to the linear time scales.

Time-calibration of the semiconductor charged particle detector using the ThC' α-particle source

1975 ◽  
Vol 127 (4) ◽  
pp. 601-602
Author(s):  
M. Matoba ◽  
J. Niidome ◽  
Y. Matsumoto ◽  
H. Yamamoto ◽  
N. Koori
Keyword(s):  
Charged Particle ◽  
Particle Detector ◽  
Particle Source ◽  
Time Calibration

On gyroresonance

1968 ◽  
Vol 2 (1) ◽  
pp. 59-64 ◽  
Author(s):  
M. J. Laird
Keyword(s):  
Magnetic Field ◽  
Charged Particle ◽  
Pitch Angle ◽  
Uniform Magnetic Field ◽  
Equations Of Motion ◽  
Circularly Polarized ◽  
Simple Picture

The motion of a charged particle in the field of a plane circularly polarized wave propagating along a uniform magnetic field B0 is investigated. For the wave magnetic field small compared with B0, the equations of motion simplify to those of the pendulum, and a simple picture of what happens for particles near gyro- resonance results. Expressions are found for the amplitude and period of the pitch angle oscillations. Departures from uniformity and possible applications to the magnetosphere are briefly discussed.

scholarly journals Strong Interrelation between the Short-Term Variability in the Ionosphere, Upper Mesosphere, and Winter Polar Stratosphere

2020 ◽  
Vol 12 (10) ◽  
pp. 1588
Author(s):  
Anna Yasyukevich ◽  
Irina Medvedeva ◽  
Vera Sivtseva ◽  
Marina Chernigovskaya ◽  
Petr Ammosov ◽  
...  
Keyword(s):  
High Latitude ◽  
Seasonal Variations ◽  
Joint Analysis ◽  
Time Interval ◽  
Electron Content ◽  
Jet Stream ◽  
Short Term ◽  
Total Electron ◽  
Short Period ◽  
Short Term Variability

We perform a joint analysis of short-period (up to several hours) variability in parameters of the ionosphere, the mesosphere, and the stratosphere at mid-latitude, subauroral, and high-latitude points for a long time interval. The study is based on the ionospheric total electron content (TEC) measurements and data on the OH rotational temperature at the mesopause height. We reveal similar seasonal variations in the dynamics of the short-term variability level, both in the ionosphere and the mesosphere. Maximum variability is observed during winter months and it exceeds the values in summer period up to 5–6 times. The revealed dynamics has no explicit relation to the levels of geomagnetic and solar activities. We suggest that the instabilities in the high-velocity stratospheric subauroral winter jet stream may be a source of the recorded variability seasonal variations in the ionosphere and the mesosphere. We propose a new index to estimate a short-term variability in the stratosphere. The index is shown to experience similar regular seasonal variations with a maximum during winter months. We show a clear correlation between the mesosphere/ionosphere variability indices values and the stratosphere disturbance index. The correlation is shown to be higher for the mesosphere variability index as compared with that in the ionosphere, and at the high-latitude point located closer to the jet stream. The obtained results indicate a strong interrelation between the short-period variability in the ionosphere, in the upper mesosphere, and in the subauroral stratosphere. The results contribute to elucidating the basic mechanisms for a vertical coupling between different atmospheric layers.

Determination of Solar Energetic Particle anisotropies based on four-sector measurements - Study based on STEREO/SEPT in preperation of SolO/EPT

2020 ◽  
Author(s):  
Maximilian Bruedern ◽  
Nina Dresing ◽  
Bernd Heber ◽  
Lars Berger ◽  
Alexander Kollhoff ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Pitch Angle ◽  
Radial Distance ◽  
Solar Energetic Particle ◽  
The Sun ◽  
Angle Scattering ◽  
Bootstrap Approach ◽  
The Magnetic Field ◽  
The Imf

&lt;p&gt;With the launch of Solar Orbiter (SolO) Solar Energetic Particles (SEPs) can be observed at a radial distance of 0.284 to 0.9 AU and an inclination out of the ecliptic up to 34 degree. The properties of SEP observations carry information about their source at the Sun as well as their transport through the interplanetary medium. Their energy is mostly determined close to the Sun. As SEPs propagate outward along the Interplanetary Magnetic Field (IMF) the pitch-angle with respect to the local field is systematically focused due to the radially decreasing IMF. However, stochastic changes are induced by scattering at fluctuations of the IMF. Often the first order anisotropy of SEPs is calculated to disentangle imprints of source and transport. Strong anisotropies indicate periods of weak pitch-angle scattering. Although many modeling and observational studies are based on the anisotropy, its uncertainty is often neglected which could result in inaccurate conclusions. Therefore, we propose a new method based on a bootstrap approach where we consider (1) directional instrument responses, (2) the variation of the magnetic field, and (3) the stochastic nature of detection. Here, we present our procedure and final results for different SEP events using measured data of the IMF and particle fluxes by the Solar Electron and Proton Telescope (SEPT) on board of each STEREO spacecraft. The SEPT provides four viewing directions with a view cone of 0.66 sr each on a three axis stabilized spacecraft. In contrast the Electron and Proton Telescope (EPT) on board SolO also consists of four viewing directions but each telescope has a much smaller view cone of 0.21 sr. Due to the very similar instrument setup we can apply our method both to the SEPT and EPT.&lt;/p&gt;

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