Magnetospheric sources of Pc1-2 ULF waves observed in the polar ionospheric waveguide

Energy from the outer regions of the magnetosphere may be transferred to the polar ionosphere by plasma waves. A magnetometer array operated during the Antarctic winter observed Ultra-Low-Frequency (ULF) plasma waves in the Pc 1–2 (0.1–10.0 Hz) frequency range, propagating parallel to the surface of the Earth in a waveguide or duct centred at ∼300 km altitude in the ionosphere. These compressional fast mode plasma waves most likely originated in the outer magnetosphere as shear mode plasma waves guided along the geomagnetic field. The region of origin in the magnetosphere for the waves is not certain as several widely spaced volumes map along geomagnetic field lines to a relatively close ensemble in the polar ionosphere. This paper compares the direction of propagation for the waves with signatures of magnetospheric regions geomagnetically projecting onto the ionosphere. Regions such as the polar cusp, low latitude boundary layer and mantle were observed by DMSP spacecraft and a SuperDARN high-frequency radar. The most likely region in the polar ionosphere for the fast mode waves to have originated from is equatorwards of the polar cusp, suggesting the field guided waves originated just inside the magnetopause. A case is made for association of the observed Pc1-2 ULF waves with post-noon, field-aligned-current systems driven by reconnection of the solar Interplanetary Magnetic Field (IMF) and the geomagnetic field near the magnetopause.

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Polarization properties of standing shear Alfvén waves in non-axisymmetric background magnetic fields

Annales Geophysicae ◽

10.5194/angeo-25-815-2007 ◽

2007 ◽

Vol 25 (3) ◽

pp. 815-822 ◽

Cited By ~ 25

Author(s):

K. Kabin ◽

R. Rankin ◽

I. R. Mann ◽

A. W. Degeling ◽

R. Marchand

Keyword(s):

Geomagnetic Field ◽

Radiation Belt ◽

Low Frequency ◽

Alfven Waves ◽

Alfvén Waves ◽

Ulf Waves ◽

Outer Radiation Belt ◽

Simple Description ◽

The Waves ◽

Shear Alfven Waves

Abstract. In this paper we present results concerning periods and polarizations of cold plasma ultra-low frequency (ULF) guided Alfvén waves in a non-axisymmetric geomagnetic field. The background geomagnetic field is approximated by a compressed dipole for which we propose a simple description in terms of Euler potentials. This study is motivated by the problem of outer-radiation belt electron acceleration by ULF waves, for which the polarization of the wave is of paramount importance. We consider an approximation appropriate to decoupled Alfvénic waves and find that the polarization of the waves can change significantly with local time. Therefore, the ULF wave's contribution to the MeV electron energization process can be localized in space.

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Helicity waves propagating in a plasma

Journal of Plasma Physics ◽

10.1017/s0022377800015841 ◽

1991 ◽

Vol 45 (3) ◽

pp. 481-488 ◽

Cited By ~ 9

Author(s):

Z. Yoshida

Keyword(s):

Magnetic Field ◽

Faraday Effect ◽

Low Frequency ◽

Plasma Waves ◽

Frequency Limit ◽

High Frequencies ◽

Transverse Modes ◽

Longitudinal Part ◽

The Waves ◽

Perturbed Magnetic Field

There exist plasma waves that transport helicity although they do not propagate electromagnetic energy. The dispersion relations of such helicity waves are studied. The electric field of the waves is parallel to the perturbed magnetic field, and both are perpendicular to the perturbed current. In cross-field propagation, a helicity wave is decomposed into two transverse modes with different polarizations and a longitudinal part. The helicity waves are principally Alfvénic in the low-frequency limit. At high frequencies, the Faraday effect comes into the polarization.

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Mars-solar wind interaction in a global hybrid model: plasma waves and ion dynamics

10.5194/egusphere-egu21-2454 ◽

2021 ◽

Author(s):

Riku Jarvinen ◽

Esa Kallio ◽

Tuija Pulkkinen

Keyword(s):

Solar Wind ◽

Large Scale ◽

Low Frequency ◽

Plasma Waves ◽

Ion Dynamics ◽

Solar Wind Interaction ◽

3 Dimensional ◽

Plasma Environment ◽

A Charge ◽

The Waves

We discuss the solar wind interaction with Mars in a self-consistent, 3-dimensional global hybrid simulation, where ions are treated as macroscopic particle clouds moving under the Lorentz force and electrons form a charge-neutralizing fluid. In the model, ion populations include both the solar wind and planetary ions. We concentrate on the formation of plasma waves near Mars. Especially, we analyze properties of large-scale waves in the ion foreshock and their transmission in the magnetosheath. Further, we study the coupling of the waves with ion dynamics in the Martian plasma environment. We discuss the solar wind interaction with Mars in a self-consistent, 3-dimensional global hybrid simulation, where ions are treated as macroscopic particle clouds moving under the Lorentz force and electrons form a charge-neutralizing fluid. In the model, ion populations include both the solar wind and planetary ions. We concentrate on the formation of plasma waves near Mars. Especially, we analyze properties of large-scale waves in the ion foreshock and their transmission in the magnetosheath. Further, we study the coupling of the waves with ion dynamics in the Martian plasma environment. Finally, we compare these Mars simulations to our earlier global hybrid modeling of Venus and Mercury to investigate how the waves and ion dynamics depend on the distance from the Sun and the size of a planetary plasma environment.References:Jarvinen R., Alho M., Kallio E., Pulkkinen T.I., 2020, Oxygen Ion Escape From Venus Is Modulated by Ultra-Low Frequency Waves, Geophys. Res. Lett., 47, 11, doi:10.1029/2020GL087462Jarvinen R., Alho M., Kallio E., Pulkkinen T.I., 2020, Ultra-low frequency waves in the ion foreshock of Mercury: A global hybrid modeling study, Mon. Notices Royal Astron. Soc., 491, 3, 4147-4161, doi:10.1093/mnras/stz3257&#160;

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Determination of wave vectors using the phase differencing method

Annales Geophysicae ◽

10.5194/angeo-31-1611-2013 ◽

2013 ◽

Vol 31 (9) ◽

pp. 1611-1617 ◽

Cited By ~ 4

Author(s):

S. N. Walker ◽

I. Moiseenko

Keyword(s):

Wave Packet ◽

Correlation Length ◽

Coherence Length ◽

Low Frequency ◽

Plasma Waves ◽

Mhd Waves ◽

Space Plasmas ◽

The Waves ◽

Theoretical Results

Abstract. Due to the collisionless nature of space plasmas, plasma waves play an important role in the redistribution of energy between the various particle populations in many regions of geospace. In order to fully comprehend such mechanisms it is necessary to characterise the nature of the waves present. This involves the determination of properties such as wave vector k. There are a number of methods used to calculate k based on the multipoint measurements that are now available. These methods rely on the fact that the same wave packet is simultaneously observed at two or more locations whose separation is small in comparison to the correlation length of the wave packet. This limitation restricts the analysis to low frequency (MHD) waves. In this paper we propose an extension to the phase differencing method to enable the correlation of measurements that were not made simultaneously but differ temporally by a number of wave periods. The method is illustrated using measurements of magnetosonic waves from the Cluster STAFF search coil magnetometer. It is shown that it is possible to identify wave packets whose coherence length is much less than the separation between the measurement locations. The resulting dispersion is found to agree with theoretical results.

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Core–skin debonding detection in honeycomb sandwich structures through guided wave wavefield analysis

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18758180 ◽

2018 ◽

Vol 30 (9) ◽

pp. 1306-1317 ◽

Cited By ~ 10

Author(s):

Lingyu Yu ◽

Zhenhua Tian ◽

Xiaopeng Li ◽

Rui Zhu ◽

Guoliang Huang

Keyword(s):

Guided Waves ◽

Sandwich Structures ◽

Lamb Waves ◽

Laser Doppler Vibrometer ◽

Low Frequency ◽

Guided Wave ◽

Honeycomb Sandwich ◽

Debonding Detection ◽

The Waves ◽

Detection And Quantification

Ultrasonic guided waves have proven to be an effective and efficient method for damage detection and quantification in various plate-like structures. In honeycomb sandwich structures, wave propagation and interaction with typical defects such as hidden debonding damage are complicated; hence, the detection of defects using guided waves remains a challenging problem. The work presented in this article investigates the interaction of low-frequency guided waves with core–skin debonding damage in aluminum core honeycomb sandwich structures using finite element simulations. Due to debonding damage, the waves propagating in the debonded skin panel change to fundamental antisymmetric Lamb waves with different wavenumber values. Exploiting this mechanism, experimental inspection using a non-contact laser Doppler vibrometer was performed to acquire wavefield data from pristine and debonded structures. The data were then processed and analyzed with two wavefield data–based imaging approaches, the filter reconstruction imaging and the spatial wavenumber imaging. Both approaches can clearly indicate the presence, location, and size of the debonding in the structures, thus proving to be effective methods for debonding detection and quantification for honeycomb sandwich structures.

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Propagation and dispersion of electrostatic waves in the ionospheric E region

Annales Geophysicae ◽

10.1007/s00585-997-0878-4 ◽

1997 ◽

Vol 15 (7) ◽

pp. 878-889 ◽

Cited By ~ 10

Author(s):

K. Iranpour ◽

H. L. Pécseli ◽

J. Trulsen ◽

A. Bahnsen ◽

F. Primdahl ◽

...

Keyword(s):

Hall Current ◽

Low Frequency ◽

Plasma Waves ◽

Electrostatic Waves ◽

Field Fluctuations ◽

E Region ◽

Band Pass ◽

Electrostatic Fluctuations ◽

The Waves ◽

The Rose

Abstract. Low-frequency electrostatic fluctuations in the ionospheric E region were detected by instruments on the ROSE rockets. The phase velocity and dispersion of plasma waves in the ionospheric E region are determined by band-pass filtering and cross-correlating data of the electric-field fluctuations detected by the probes on the ROSE F4 rocket. The results were confirmed by a different method of analysis of the same data. The results show that the waves propagate in the Hall-current direction with a velocity somewhat below the ion sound speed obtained for ionospheric conditions during the flight. It is also found that the waves are dispersive, with the longest wavelengths propagating with the lowest velocity.

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Determining the Polar Cusp Longitudinal Location from Pc5 Geomagnetic Field Measurements at a Pair of High Latitude Stations

Proceedings of the International Astronomical Union ◽

10.1017/s174392131701002x ◽

2017 ◽

Vol 13 (S335) ◽

pp. 139-141

Author(s):

Stefania Lepidi ◽

Patrizia Francia ◽

Lili Cafarella ◽

Domenico Di Mauro ◽

Martina Marzocchetti

Keyword(s):

Magnetic Field ◽

Satellite Data ◽

High Latitude ◽

Geomagnetic Field ◽

Geomagnetic Latitude ◽

Low Frequency ◽

Field Measurements ◽

Polar Cap ◽

Polar Cusp ◽

Local Noon

AbstractWe use low frequency geomagnetic field measurements at two Antarctic stations to statistically investigate the longitudinal location of the polar cusp. The two stations are both located in the polar cap at a geomagnetic latitude close to the cusp latitude; they are separated by one hour in magnetic local time. At each station the Pc5 power maximizes when the station approaches the cusp, i.e. around magnetic local noon. The comparison between the Pc5 power at the two stations allows to determine the longitudinal location of the cusp. Our analysis is conducted considering separately different orientation of the interplanetary magnetic field. The results, which indicate longitudinal shifts of the polar cusp depending on the selected conditions, are discussed in relation to previous studies of the polar cusp location based on polar magnetospheric satellite data.

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Improving accuracy through density correction in guided wave tomography

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2015.0832 ◽

2016 ◽

Vol 472 (2186) ◽

pp. 20150832 ◽

Cited By ~ 9

Author(s):

P. Huthwaite

Keyword(s):

Guided Waves ◽

Low Frequency ◽

Region Of Interest ◽

Density Variation ◽

Pressure Vessels ◽

Guided Wave ◽

Wave Tomography ◽

Wall Loss ◽

Improving Accuracy ◽

The Waves

The accurate quantification of wall loss caused by corrosion is critical to the reliable life estimation of pipes and pressure vessels. Traditional thickness gauging by scanning a probe is slow and requires access to all points on the surface; this is impractical in many cases as corrosion often occurs where access is restricted, such as beneath supports where water collects. Guided wave tomography presents a solution to this; by transmitting guided waves through the region of interest and exploiting their dispersive nature, it is possible to build up a map of thickness. While the best results have been seen when using the fundamental modes A0 and S0 at low frequency, the complex scattering of the waves causes errors within the reconstruction. It is demonstrated that these lead to an underestimate in wall loss for A0 but an overestimate for S0. Further analysis showed that this error was related to density variation, which was proportional to thickness. It was demonstrated how this could be corrected for in the reconstructions, in many cases resulting in the near-elimination of the error across a range of defects, and greatly improving the accuracy of life estimates from guided wave tomography.

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