NDLI: The Effect of Ion Flow Shear on Electrostatic Ion-Cyclotron Waves

Content Provider	IEEE Xplore Digital Library
Author	Merlino, R.L. Kim, S. D'Angelo, N. Ganguli, G.I.
Copyright Year	2005
Description	Author affiliation: Dept. Phys. & Astron., Iowa Univ., Iowa City, IA (Merlino, R.L.; Kim, S.; D'Angelo, N.)
Abstract	Summary form only given. Plasma waves near the ion gyrofrequency, propagating nearly perpendicular to the Earth's magnetic field, have often been observed on satellites in the auroral region. The excitation of these waves has traditionally been attributed to an electrostatic ion-cyclotron (EIC) instability driven by magnetic field-aligned currents. One problem with this scenario has been that often the waves were observed in association with currents that were below the theoretical excitation threshold. Also, while the wave spectrum was expected to be narrowband and structured around a few cyclotron harmonics, a broadband frequency spectrum was often reported. Ganguli and his associates suggested that transverse gradients in the ion flow along the magnetic field (ion flow shear) could provide a mechanism for EIC wave generation, either in addition to the field-aligned currents, or in the absence of field-aligned currents. They showed further, that since the critical shear required to excite EIC waves was approximately independent of the cyclotron wave harmonic number, ion flow shear could generate higher cyclotron harmonics, a common signature of the auroral observations. In the work presented here, the effect of ion flow shear on the excitation of EIC waves was studied experimentally in a double-ended Q-machine. An annular region of ion flow shear was produced by using a ring+disk configuration, as described by Kim et al. Waves with frequencies near the ion gyrofrequency and multiple harmonics were launched from an antenna into a plasma with no field-aligned electron current. As the EIC waves propagated across the magnetic field through a region with ion flow shear, the waves were observed to grow in amplitude. The simultaneous excitation of a multi-harmonic EIC spectrum was also observed when a broadband signal from a white noise source was applied to the antenna.
Sponsorship	Plasma Sci. Appl. Comm. IEEE Nucl. Plasma Sci. Soc.
Starting Page	347
Ending Page	347
File Size	993298
Page Count	1
File Format	PDF
ISBN	0780393007
ISSN	07309244
DOI	10.1109/PLASMA.2005.359504
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2005-06-20
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Electrostatics Magnetic fields Cyclotrons Plasma waves Frequency Antennas and propagation Broadband antennas Earth Satellites Narrowband
Content Type	Text
Resource Type	Article
Subject	Atomic and Molecular Physics, and Optics Condensed Matter Physics Electrical and Electronic Engineering

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in