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Review the mechanism by which we measure coronal
magnetic fields with radio techniques |
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Discuss examples of observations |
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Discuss problem of 3D analysis |
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Constraints for FASR |
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Opacity results from electrons gyrating in
coronal magnetic fields at fB = 2.8 106 B Hz. |
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In the non-flare (non-relativistic) corona this
produces narrow resonances. |
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Opacity µ
n B/(¶B/¶l) (T/mc2 sin2q)s-1 where s = 1, 2, 3, … is the harmonic |
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Because T/mc2 is 1/3000, opacity
drops by 3 orders of magnitude from one layer to the next |
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Radio observations still the only means for
reliably measuring coronal magnetic field strengths anywhere on the solar
disk |
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Measures temperatures on surface of constant
field strength – directly see regions of strong heating |
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Because emission is optically thick in regions
of strong field, we get 3D information on fields |
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Relatively insensitive to density, therefore
complements EUV/soft X-ray observations which are dominated by density
contrast |
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Important role in testing techniques for
extrapolating surface fields into corona |
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Notes