Growth Rates of the Upper-Hybrid Waves for Power-Law and Kappa Distributions with a Loss-Cone Anisotropy

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F19%3A00109332" target="_blank" >RIV/00216224:14310/19:00109332 - isvavai.cz</a>

Výsledek na webu

<a href="https://link.springer.com/article/10.1007/s11207-019-1415-9" target="_blank" >https://link.springer.com/article/10.1007/s11207-019-1415-9</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s11207-019-1415-9" target="_blank" >10.1007/s11207-019-1415-9</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Growth Rates of the Upper-Hybrid Waves for Power-Law and Kappa Distributions with a Loss-Cone Anisotropy

Popis výsledku v původním jazyce

Fine structures of radio bursts play an important role in the diagnostics of the solar flare plasma. Among them the zebras, which are prevalently assumed to be generated by the double-plasma resonance instability, belong to the most important ones. In this paper we compute the growth rate of this instability for two types of the electron distribution: a)for the power-law distribution and b)for the kappa distribution, in both cases with the loss-cone type anisotropy. We find that the growth rate of the upper-hybrid waves for the power-law momentum distribution strongly depends on the pitch-angle boundary. The maximum growth rate is found for the pitch angle c approximate to 50 degrees. For small angles the growth rate profile is very flat and for high pitch angles the wave absorption occurs. Furthermore, analyzing the growth rate of the upper-hybrid waves for the kappa momentum distribution we find that a decrease of the characteristic momentum p shifts the maximum of the growth rate to lower values of the ratio of the electron-plasma and electron-cyclotron frequencies, and the frequency widths of the growth rate peaks are very broad. But if we consider the kappa distribution which is isotropic up to some large momentum pm and anisotropic with loss-cone above this momentum then distinct peaks of the growth rate appear and thus distinct zebra stripes can be generated. It means that the restriction of small momenta for the anisotropic part of distributions is of principal importance for the zebra stripe generation. Finally, for the zebra stripes observed on 1 August 2010, the growth rates in dependence on the radio frequency are computed. It is shown that in this case the growth rate peaks are more distinct than in usually presented dependencies of growth rates on the ratio of the plasma and cyclotron frequencies.

Název v anglickém jazyce

Growth Rates of the Upper-Hybrid Waves for Power-Law and Kappa Distributions with a Loss-Cone Anisotropy

Popis výsledku anglicky

Fine structures of radio bursts play an important role in the diagnostics of the solar flare plasma. Among them the zebras, which are prevalently assumed to be generated by the double-plasma resonance instability, belong to the most important ones. In this paper we compute the growth rate of this instability for two types of the electron distribution: a)for the power-law distribution and b)for the kappa distribution, in both cases with the loss-cone type anisotropy. We find that the growth rate of the upper-hybrid waves for the power-law momentum distribution strongly depends on the pitch-angle boundary. The maximum growth rate is found for the pitch angle c approximate to 50 degrees. For small angles the growth rate profile is very flat and for high pitch angles the wave absorption occurs. Furthermore, analyzing the growth rate of the upper-hybrid waves for the kappa momentum distribution we find that a decrease of the characteristic momentum p shifts the maximum of the growth rate to lower values of the ratio of the electron-plasma and electron-cyclotron frequencies, and the frequency widths of the growth rate peaks are very broad. But if we consider the kappa distribution which is isotropic up to some large momentum pm and anisotropic with loss-cone above this momentum then distinct peaks of the growth rate appear and thus distinct zebra stripes can be generated. It means that the restriction of small momenta for the anisotropic part of distributions is of principal importance for the zebra stripe generation. Finally, for the zebra stripes observed on 1 August 2010, the growth rates in dependence on the radio frequency are computed. It is shown that in this case the growth rate peaks are more distinct than in usually presented dependencies of growth rates on the ratio of the plasma and cyclotron frequencies.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Solar Physics

ISSN

0038-0938

e-ISSN

1573-093X

Svazek periodika

294

Číslo periodika v rámci svazku

3

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

14

Strana od-do

29

Kód UT WoS článku

000460482700001

EID výsledku v databázi Scopus

2-s2.0-85062641187