Zebra Stripes with High Gyro-Harmonic Numbers

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F22%3A00560480" target="_blank" >RIV/67985815:_____/22:00560480 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0334207" target="_blank" >https://hdl.handle.net/11104/0334207</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s11207-022-02036-y" target="_blank" >10.1007/s11207-022-02036-y</a>

Result language

angličtina

Original language name

Zebra Stripes with High Gyro-Harmonic Numbers

Original language description

Solar radio zebras are used in the determination of the plasma density and magnetic field in solar flare plasmas. Analyzing observed zebra stripes and assuming their generation by the double-plasma resonance (DPR) instability, high values of the gyro-harmonic number are found. In some cases they exceed one hundred, in disagreement with the DPR growth rates computed up to now, which decrease with increasing gyro-harmonic number. We address the question of how zebras with high values of the gyro-harmonic numbers s are generated. For this purpose, we compute the growth rates of the DPR instability in a very broad range of s, considering a loss-cone kappa-distribution of superthermal electrons and varying the losscone angle, electron energies, and background plasma temperature. We have numerically calculated the dispersion relations and the growth rates of the upper-hybrid waves and found that the growth rates increase with increasing gyro-harmonic numbers if the loss-cone angles are similar to 80 degrees. The highest growth rates for these loss-cone angles are obtained for velocity v(k) = 0.15 c. The growth rates as a function of the gyro-harmonic number still show well distinct peaks, which correspond to zebra-stripe frequencies. The contrast between peak growth rates and surrounding growth rate levels increases as the kappa index increases and the background temperature decreases. Zebras with high values of s can be generated in regions where loss-cone distributions of superthermal electrons with large loss-cone angles (similar to 80 degrees) are present. Furthermore, owing to the high values of s, the magnetic field is relatively weak and has a small spatial gradient in such regions.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Solar Physics

ISSN

0038-0938

e-ISSN

1573-093X

Volume of the periodical

297

Issue of the periodical within the volume

8

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

16

Pages from-to

103

UT code for WoS article

000842188900003

EID of the result in the Scopus database

2-s2.0-85136526677