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Record 2 of 14463
Combined Modeling of Acceleration, Transport, and Hydrodynamic Response in Solar Flares. 1; The Numerical Model
External Online Source: doi:10.1088/0004-637X/702/2/1553
Author and Affiliation:
Liu, Wei(Stanford-Lockheed Inst. for Space Research, Dept. of Physics, Stanford, CA, United States)
Petrosian, Vahe(Stanford-Lockheed Inst. for Space Research, Dept. of Physics, Stanford, CA, United States)
Mariska, John T.(Naval Research Lab., Washington, DC, United States)
Abstract: Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares, but for convenience and simplicity they were artificially separated in the past. We present here self consistently combined Fokker-Planck modeling of particles and hydrodynamic simulation of flare plasma. Energetic electrons are modeled with the Stanford unified code of acceleration, transport, and radiation, while plasma is modeled with the Naval Research Laboratory flux tube code. We calculated the collisional heating rate directly from the particle transport code, which is more accurate than those in previous studies based on approximate analytical solutions. We repeated the simulation of Mariska et al. with an injection of power law, downward-beamed electrons using the new heating rate. For this case, a -10% difference was found from their old result. We also used a more realistic spectrum of injected electrons provided by the stochastic acceleration model, which has a smooth transition from a quasi-thermal background at low energies to a non thermal tail at high energies. The inclusion of low-energy electrons results in relatively more heating in the corona (versus chromosphere) and thus a larger downward heat conduction flux. The interplay of electron heating, conduction, and radiative loss leads to stronger chromospheric evaporation than obtained in previous studies, which had a deficit in low-energy electrons due to an arbitrarily assumed low-energy cutoff. The energy and spatial distributions of energetic electrons and bremsstrahlung photons bear signatures of the changing density distribution caused by chromospheric evaporation. In particular, the density jump at the evaporation front gives rise to enhanced emission, which, in principle, can be imaged by X-ray telescopes. This model can be applied to investigate a variety of high-energy processes in solar, space, and astrophysical plasmas.
Publication Date: Sep 10, 2009
Document ID:
20100017245
(Acquired May 05, 2010)
Subject Category: SOLAR PHYSICS
Report/Patent Number: AD-A513382
Document Type: Journal Article
Publication Information: The Astrophysical Journal; Volume 702; 1553-1566
Publisher Information: American Astronomical Society, Washington, DC, United States
Contract/Grant/Task Num: NNM09AA01C; NSF ATM 0312344; NAG5 12111; NAG5 11918-1
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD, United States
NASA; Washington, DC United States
NASA Marshall Space Flight Center; Huntsville, AL, United States
National Science Foundation; Arlington, VA, United States
Naval Research Lab.; Washington, DC, United States
Description: 15p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ACCELERATION (PHYSICS); HYDRODYNAMICS; MATHEMATICAL MODELS; SOLAR FLARES; STOCHASTIC PROCESSES; SPACE PLASMAS; CHROMOSPHERE; SOLAR X-RAYS; AEROSPACE ENVIRONMENTS; BREMSSTRAHLUNG; ELECTRONS; EVAPORATION; FLUID DYNAMICS; FOKKER-PLANCK EQUATION; GAMMA RAYS; HEAT FLUX; SPATIAL DISTRIBUTION
Other Descriptors: HIGH ENERGY; ACCELERATION; TRANSPORT; SOLAR FLARES; HYDRODYNAMICS; LOW ENERGY; AEROSPACE ENVIRONMENTS; GAMMA RAYS; EVAPORATION; FLUID DYNAMICS; HEAT FLUX; SOLAR X RAYS; FOKKER PLANCK EQUATIONS; CHROMOSPHERE; ELECTRONS; RADIATION; REPRINTS; BREMSSTRAHLUNG; MATHEMATICAL MODELS; SPATIAL DISTRIBUTION; ACCELERATION OF PARTICLES; STOCHASTIC ACCELERATION MODEL; ATMOSPHERIC PLASMA
Miscellaneous Notes: Sponsored in part by NSF under Grant No. ATM-0312344 and by NRL
Availability Source: Other Sources
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