Second harmonic emission during solar flares

Type III (type U) radio bursts are signatures of energetic electrons generated during solar flares, traveling along open (closed) magnetic coronal field lines. The burst photons correspond to the second harmonic of the plasma frequency and are generated by the coalescence of two Langmuir waves excit...

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Autores principales:	Vásquez, A.M., Gómez, D.O., Fontán, C.F.
Formato:	JOUR
Materias:	Sun: flares Sun: radio radiation Turbulence
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_0004637X_v564_n2I_p1035_Vasquez
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_0004637X_v564_n2I_p1035_Vasquez
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spelling	todo:paper_0004637X_v564_n2I_p1035_Vasquez2023-10-03T14:01:49Z Second harmonic emission during solar flares Vásquez, A.M. Gómez, D.O. Fontán, C.F. Sun: flares Sun: radio radiation Turbulence Type III (type U) radio bursts are signatures of energetic electrons generated during solar flares, traveling along open (closed) magnetic coronal field lines. The burst photons correspond to the second harmonic of the plasma frequency and are generated by the coalescence of two Langmuir waves excited by the beam. In the present paper we derive expressions for the emissivity and absorption in the second harmonic of the plasma frequency without assuming the so-called head-on approximation. Only plasma wave isotropy is assumed. The resulting expressions yield important reductions in the emissivity when compared to the head-on results, as well as to lower absorption coefficients. We calculate second harmonic emissivities for several electron beam intensities. The spectrum of Langmuir turbulence used to compute second harmonic emissivity is consistently derived from a model that includes collisional effects and quasilinear relaxation. We speculate that further reductions in the emissivity, down to levels compatible with observations, would be obtained if nonlinear scattering of Langmuir waves with ion-acoustic turbulence and background density inhomogeneities are considered. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0004637X_v564_n2I_p1035_Vasquez
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Sun: flares Sun: radio radiation Turbulence
spellingShingle	Sun: flares Sun: radio radiation Turbulence Vásquez, A.M. Gómez, D.O. Fontán, C.F. Second harmonic emission during solar flares
topic_facet	Sun: flares Sun: radio radiation Turbulence
description	Type III (type U) radio bursts are signatures of energetic electrons generated during solar flares, traveling along open (closed) magnetic coronal field lines. The burst photons correspond to the second harmonic of the plasma frequency and are generated by the coalescence of two Langmuir waves excited by the beam. In the present paper we derive expressions for the emissivity and absorption in the second harmonic of the plasma frequency without assuming the so-called head-on approximation. Only plasma wave isotropy is assumed. The resulting expressions yield important reductions in the emissivity when compared to the head-on results, as well as to lower absorption coefficients. We calculate second harmonic emissivities for several electron beam intensities. The spectrum of Langmuir turbulence used to compute second harmonic emissivity is consistently derived from a model that includes collisional effects and quasilinear relaxation. We speculate that further reductions in the emissivity, down to levels compatible with observations, would be obtained if nonlinear scattering of Langmuir waves with ion-acoustic turbulence and background density inhomogeneities are considered.
format	JOUR
author	Vásquez, A.M. Gómez, D.O. Fontán, C.F.
author_facet	Vásquez, A.M. Gómez, D.O. Fontán, C.F.
author_sort	Vásquez, A.M.
title	Second harmonic emission during solar flares
title_short	Second harmonic emission during solar flares
title_full	Second harmonic emission during solar flares
title_fullStr	Second harmonic emission during solar flares
title_full_unstemmed	Second harmonic emission during solar flares
title_sort	second harmonic emission during solar flares
url	http://hdl.handle.net/20.500.12110/paper_0004637X_v564_n2I_p1035_Vasquez
work_keys_str_mv	AT vasquezam secondharmonicemissionduringsolarflares AT gomezdo secondharmonicemissionduringsolarflares AT fontancf secondharmonicemissionduringsolarflares
_version_	1782024291727966208

Second harmonic emission during solar flares

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