Radioastronomical Remote Sensing of Turbulence and Current Sheets

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Radioastronomical Remote Sensing of Turbulence and Current Sheets in the Solar Corona Steven R.

Radioastronomical Remote Sensing of Turbulence and Current Sheets in the Solar Corona Steven R. Spangler Department of Physics and Astronomy University of Iowa

The concept of coronal Faraday Rotation

The concept of coronal Faraday Rotation

Plasma Contributions to the Faraday Rotation Integral We need enough observations to sort out

Plasma Contributions to the Faraday Rotation Integral We need enough observations to sort out various contributions to coronal density and magnetic field

Differential Faraday Rotation A difference in Rotation Measure between two closely-spaced lines of sight

Differential Faraday Rotation A difference in Rotation Measure between two closely-spaced lines of sight

Coronal Heating Mechanisms: AC vs DC In DC mechanisms, heating is done by currents

Coronal Heating Mechanisms: AC vs DC In DC mechanisms, heating is done by currents (possibly turbulent) in the corona. We want to measure these currents

Coronal Heating Mechanisms: AC vs DC In DC mechanisms, heating is done by currents

Coronal Heating Mechanisms: AC vs DC In DC mechanisms, heating is done by currents (possibly turbulent) in the corona. We want to measure these currents

Differential Faraday Rotation and Ampere’s Law

Differential Faraday Rotation and Ampere’s Law

Differential Faraday Rotation and Ampere’s Law II Method utilized in Wisconsin Reversed Field Pinch

Differential Faraday Rotation and Ampere’s Law II Method utilized in Wisconsin Reversed Field Pinch (RFP) by Ding, Brower, et al (PRL 90, 035002, 2003)

Observations of Differential Faraday Rotation on August 16, 18 2004 Total Faraday Rotation Differential

Observations of Differential Faraday Rotation on August 16, 18 2004 Total Faraday Rotation Differential Faraday Rotation

Estimates of Coronal Currents 0. 3 GAmp 1. 0 GAmp Smaller measurements of ~

Estimates of Coronal Currents 0. 3 GAmp 1. 0 GAmp Smaller measurements of ~ 0. 1 Gamp for Aug. 18, 2003

Ampere’s Law and Coronal Heating • Having I does not directly give volumetric heating

Ampere’s Law and Coronal Heating • Having I does not directly give volumetric heating rate. • Need to know number, length, and thickness of current sheets, and resistivity for volumetric heating rate.

Conclusions • Differential FR measurements with VLA give electrical current inside boxes of various

Conclusions • Differential FR measurements with VLA give electrical current inside boxes of various sizes. • Values of order 0. 1 – 1 G-Amp • Future observations could improve on these results. • Targeted observations (such as good sources occulted by streamers). • Observations closer to Sun at 5 GHz. • And thanks to :