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Title: Experimental Study of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet

Abstract

The role of turbulence in the process of magnetic reconnection has been the subject of a great deal of study and debate in the theoretical literature. At issue in this debate is whether turbulence is essential for fast magnetic reconnection to occur in collisionless current sheets. Some theories claim it is necessary in order to provide anomalous resistivity, while others present a laminar fast reconnection mechanism based on the Hall term in the generalized Ohm's law. In this work, a thorough study of electrostatic potential fluctuations in the current sheet of the Magnetic Reconnection Experiment (MRX) [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] was performed in order to ascertain the importance of turbulence in a laboratory reconnection experiment. Using amplified floating Langmuir probes, broadband fluctuations in the lower hybrid frequency range (fLH approximately 5-15 MHz) were measured which arise with the formation of the current sheet in MRX. The frequency spectrum, spatial amplitude profile, and spatial correlation characteristics of the measured turbulence were examined carefully, finding consistency with theories of the lower-hybrid drift instability (LHDI). The LHDI and its role in magnetic reconnection has been studied theoretically for decades, but this work represents the first detection and detailedmore » study of the LHDI in a laboratory current sheet. The observation of the LHDI in MRX has provided the unique opportunity to uncover the role of this instability in collisionless reconnection. It was found that: (1) the LHDI fluctuations are confined to the low-beta edge of current sheets in MRX; (2) the LHDI amplitude does not correlate well in time or space with the reconnection electric field, which is directly related to the rate of reconnection; and (3) significant LHDI amplitude persists in high collisionality current sheets where the reconnection rate is classical. These findings suggest that the measured LHDI fluctuations do not play an essential role in determining the reconnection rate in MRX.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Princeton Plasma Physics Lab., NJ (US)
Sponsoring Org.:
USDOE Office of Science (US)
OSTI Identifier:
798197
Report Number(s):
PPPL-3708.pdf
TRN: US0202154
DOE Contract Number:  
AC02-76CH03073
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 18 Jun 2002
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; DETECTION; DRIFT INSTABILITY; ELECTRIC FIELDS; ELECTROSTATICS; FLUCTUATIONS; FREQUENCY RANGE; INSTABILITY; LANGMUIR PROBE; MAGNETIC RECONNECTION; TURBULENCE

Citation Formats

Carter, T. A., Yamada, M., Ji, H., Kulsrud, R. M., and Trintchouck, F. Experimental Study of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet. United States: N. p., 2002. Web. doi:10.2172/798197.
Carter, T. A., Yamada, M., Ji, H., Kulsrud, R. M., & Trintchouck, F. Experimental Study of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet. United States. https://doi.org/10.2172/798197
Carter, T. A., Yamada, M., Ji, H., Kulsrud, R. M., and Trintchouck, F. Tue . "Experimental Study of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet". United States. https://doi.org/10.2172/798197. https://www.osti.gov/servlets/purl/798197.
@article{osti_798197,
title = {Experimental Study of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet},
author = {Carter, T. A. and Yamada, M. and Ji, H. and Kulsrud, R. M. and Trintchouck, F.},
abstractNote = {The role of turbulence in the process of magnetic reconnection has been the subject of a great deal of study and debate in the theoretical literature. At issue in this debate is whether turbulence is essential for fast magnetic reconnection to occur in collisionless current sheets. Some theories claim it is necessary in order to provide anomalous resistivity, while others present a laminar fast reconnection mechanism based on the Hall term in the generalized Ohm's law. In this work, a thorough study of electrostatic potential fluctuations in the current sheet of the Magnetic Reconnection Experiment (MRX) [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] was performed in order to ascertain the importance of turbulence in a laboratory reconnection experiment. Using amplified floating Langmuir probes, broadband fluctuations in the lower hybrid frequency range (fLH approximately 5-15 MHz) were measured which arise with the formation of the current sheet in MRX. The frequency spectrum, spatial amplitude profile, and spatial correlation characteristics of the measured turbulence were examined carefully, finding consistency with theories of the lower-hybrid drift instability (LHDI). The LHDI and its role in magnetic reconnection has been studied theoretically for decades, but this work represents the first detection and detailed study of the LHDI in a laboratory current sheet. The observation of the LHDI in MRX has provided the unique opportunity to uncover the role of this instability in collisionless reconnection. It was found that: (1) the LHDI fluctuations are confined to the low-beta edge of current sheets in MRX; (2) the LHDI amplitude does not correlate well in time or space with the reconnection electric field, which is directly related to the rate of reconnection; and (3) significant LHDI amplitude persists in high collisionality current sheets where the reconnection rate is classical. These findings suggest that the measured LHDI fluctuations do not play an essential role in determining the reconnection rate in MRX.},
doi = {10.2172/798197},
url = {https://www.osti.gov/biblio/798197}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2002},
month = {6}
}