scholarly journals Proton-Alpha Drift Instability of Electromagnetic Ion-Cyclotron Modes: Quasilinear Development

Physics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 1175-1189
Author(s):  
Shaaban M. Shaaban ◽  
Marian Lazar ◽  
Peter H. Yoon ◽  
Stefaan Poedts ◽  
Rodrigo A. López
Keyword(s):  
Solar Wind ◽  
Observational Data ◽  
Parametric Analysis ◽  
Alpha Particles ◽  
Space Plasmas ◽  
High Interest ◽  
Ion Cyclotron ◽  
Temperature Contrast ◽  
Drift Instability

The ability of space plasmas to self-regulate through mechanisms involving self-generated fluctuations is a topic of high interest. This paper presents the results of a new advanced quasilinear (QL) approach for the instability of electromagnetic ion-cyclotron modes driven by the relative alpha-proton drift observed in solar wind. For an extended parametric analysis, the present QL approach includes also the effects of intrinsic anisotropic temperatures of these populations. The enhanced fluctuations contribute to an exchange of energy between proton and alpha particles, leading to important variations of the anisotropies, the proton-alpha drift and the temperature contrast. The results presented here can help understand the observational data, in particular, those revealing the local variations associated with the properties of protons and alpha particles as well as the spatial profiles in the expanding solar wind.

Feasibility of Ion-cyclotron Resonant Heating in the Solar Wind

2021 ◽  
Author(s):  
Roberto E. Navarro ◽  
Victor Muñoz ◽  
Juan A. Valdivia ◽  
Pablo S. Moya
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Alpha Particles ◽  
Particle Interactions ◽  
Fermi Acceleration ◽  
Ion Cyclotron Waves ◽  
Proton Temperature ◽  
Propagating Waves ◽  
Ion Cyclotron ◽  
Cold Electrons

<p>Wave-particle interactions are believed to be one of the most important kinetic processes regulating the heating and acceleration of Solar Wind plasma. One possible explanation to the observed preferential heating of alpha (He<sup>+2</sup>) ions relies on a process similar to a second order Fermi acceleration mechanism. In this model, heavy ions are able to resonate with multiple counter-propagating ion-cyclotron waves, while protons can encounter only single resonances, resulting in the subsequent preferential energization of minor ions. In this work, we address and test this idea by calculating the number of plasma particles that are resonating with ion-cyclotron waves propagating parallel and anti-parallel to an ambient magnetic field in a proton/alpha plasma with cold electrons. Resonances are calculated through the proper kinetic multi-species dispersion relation of Alfven waves. We show that 100% of the alpha population can resonate with counter-propagating waves below a threshold ΔU<sub>αp</sub>/v<sub>A</sub><U<sub>0</sub>+a(β+β<sub>0</sub>)<sup>b</sup> in the differential streaming between protons and alpha particles, where U<sub>0</sub>=-0.532, a=1.211, β<sub>0</sub>=0.0275, and b=0.348 for isotropic ions. This threshold seems to match with constraints of the observed ΔU<sub>αp</sub> in the Solar Wind for low values of the proton plasma beta<strong>.</strong> Finally, it is also shown that this process is limited by the growth of plasma kinetic instabilities, a constraint that could explain alpha-to-proton temperature ratio observations in the Solar Wind at 1 AU.</p>

Coupling of electrostatic ion cyclotron and ion acoustic waves in the solar wind

2016 ◽  
Vol 23 (8) ◽  
pp. 082901 ◽  
Author(s):  
T. Sreeraj ◽  
S. V. Singh ◽  
G. S. Lakhina
Keyword(s):  
Solar Wind ◽  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Ion Acoustic ◽  
Ion Cyclotron

HelioSwarm: The Nature of Turbulence in Space Plasmas

2021 ◽  
Author(s):  
Harlan Spence ◽  
Kristopher Klein ◽  
HelioSwarm Science Team
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Solar Wind Plasma ◽  
Turbulent Energy ◽  
Space Plasmas ◽  
Plasma Parameters ◽  
Astrophysical Plasmas ◽  
Ion Distributions ◽  
Background Magnetic Field

<p>Recently selected for phase A study for NASA’s Heliophysics MidEx Announcement of Opportunity, the HelioSwarm Observatory proposes to transform our understanding of the physics of turbulence in space and astrophysical plasmas by deploying nine spacecraft to measure the local plasma and magnetic field conditions at many points, with separations between the spacecraft spanning MHD and ion scales.  HelioSwarm resolves the transfer and dissipation of turbulent energy in weakly-collisional magnetized plasmas with a novel configuration of spacecraft in the solar wind. These simultaneous multi-point, multi-scale measurements of space plasmas allow us to reach closure on two science goals comprised of six science objectives: (1) reveal how turbulent energy is transferred in the most probable, undisturbed solar wind plasma and distributed as a function of scale and time; (2) reveal how this turbulent cascade of energy varies with the background magnetic field and plasma parameters in more extreme solar wind environments; (3) quantify the transfer of turbulent energy between fields, flows, and ion heat; (4) identify thermodynamic impacts of intermittent structures on ion distributions; (5) determine how solar wind turbulence affects and is affected by large-scale solar wind structures; and (6) determine how strongly driven turbulence differs from that in the undisturbed solar wind. </p>

Proton Beam Abundance Variations and Their Relation to Alpha Particle Properties

2021 ◽  
Vol 923 (2) ◽  
pp. 170
Author(s):  
Tereza Ďurovcová ◽  
Jana Šafránková ◽  
Zdeněk Němeček
Keyword(s):  
Solar Wind ◽  
Proton Beam ◽  
Alpha Particle ◽  
Source Region ◽  
Radial Distance ◽  
Alpha Particles ◽  
Momentum Balance ◽  
Particle Interactions ◽  
Coulomb Collisions ◽  
Particle Properties

Abstract Less abundant but still dynamically important solar wind components are the proton beam and alpha particles, which usually contribute similarly to the total ion momentum. The main characteristics of alpha particles are determined by the solar wind source region, but the origin of the proton beam and its properties are still not fully explained. We use the plasma data measured in situ on the path from 0.3 to 1 au (Helios 1 and 2) and focus on the proton beam development with an increasing radial distance as well as on the connection between the proton beam and alpha particle properties. We found that the proton beam relative abundance increases with increasing distance from the Sun in the collisionally young streams. Among the mechanisms suggested for beam creation, we have identified the wave–particle interactions with obliquely propagating Alfvén modes being consistent with observations. As the solar wind streams get collisionally older, the proton beam decay gradually dominates and the beam abundance is reduced. In search for responsible mechanisms, we found that the content of alpha particles is correlated with the proton beam abundance, and this effect is more pronounced in the fast solar wind streams during the solar maximum. We suggest that Coulomb collisions are the main agent leading to merging of the proton beam and core. We are also showing that the variations of the proton beam abundance are correlated with a decrease of the alpha particle velocity in order to maintain the total momentum balance in the solar wind frame.

scholarly journals Pengaruh Minat dan Penggunaan Metode terhadap Hasil Belajar IPA Biologi Siswa Kelas VII SMP Negeri 2 Jayapura

2018 ◽  
Vol 1 (1) ◽  
pp. 80-94
Author(s):  
Mikael Nesi ◽  
Maik Akobiarek
Keyword(s):  
Student Learning ◽  
Learning Outcomes ◽  
Parametric Analysis ◽  
Science Learning ◽  
Student Learning Outcomes ◽  
Homogeneity Test ◽  
High Interest ◽  
Normality Test ◽  
Lecture Method ◽  
Research Type

This study aims to determine (1) The influence of interest on student learning outcomes in Biology science lessons in SMP Negeri 2 Jayapura, (2) The influence of the use of methods and interests on student learning outcomes in the science of Biology in SMP Negeri 2 Jayapura, (3) interaction between method and interest toward student learning outcomes in science biology lesson in SMP Negeri 2 Jayapura. This research type is experiment. This research took place from February to May 2017. The population of this study is all students of class VII in SMP Negeri 2 Jayapura. The sample of this research is all students of class VIIJ, VIIK, and VIIL which is divided into 4 classes. Data analysis uses prerequisite test with parametric analysis path with normality test, homogeneity test, and interest question variable data. While hypothesis testing using ANAVA two way. The results showed (1) There is an influence of interest that arise from within the students to the learning outcomes achieved in the learning process with the results of the calculation of high interest variable average 74.87 and the low interest variable average 65.04. (2) There is an average influence of Biology Science learning outcomes in students who are taught using Student Worksheet (LKS) Word Square Model from the students who taught using lecture method on students who have high interest result Fcount = 2.967 more than Ftable = 2.46. (3) There is an average influence of Biology Science learning outcomes in students who are taught using Student Worksheet (LKS) Word Square Model from the students taught using lecture method on students who have low interest result Fcount = 2.952 more than Ftable = 2.46. (4) There is a very significant influence between the learning method and the interest or the influence of the method on the learning outcomes of Biology IPA depending on the student's interest result Fcount = 3.776 more than Ftable = 2.46. Keywords: word square, interests, learning outcomes

Microinstabilities and plasma waves at Near-Sun Solar Wind collisionless Shocks: Predictions for PSP and SO

2021 ◽  
Author(s):  
Zhongwei Yang ◽  
Shuichi Matsukiyo ◽  
Huasheng Xie ◽  
Fan Guo ◽  
Mingzhe Liu ◽  
...  
Keyword(s):  
Solar Wind ◽  
Shock Front ◽  
Leading Edge ◽  
Relativistic Electrons ◽  
Interplanetary Shocks ◽  
Particle In Cell ◽  
Drift Instability ◽  
Shock Simulation ◽  
Mass Ejection ◽  
The Impact

<p><span>Microinstabilities and waves excited at perpendicular interplanetary shocks in the near-Sun solar wind are investigated by full particle-in-cell simulations. By analyzing the dispersion relation of fluctuating field components directly issued from the shock simulation, we obtain key findings concerning wave excitations at the shock front: (1) at the leading edge of the foot, two types of electrostatic (ES) waves are observed. The relative drift of the reflected ions versus the electrons triggers an electron cyclotron drift instability (ECDI) that excites the first ES wave. Because the bulk velocity of gyro-reflected ions shifts to the direction of the shock front, the resulting ES wave propagates obliquely to the shock normal. Immediately, a fraction of incident electrons are accelerated by this ES wave and a ring-like velocity distribution is generated. They can couple with the hot Maxwellian core and excite the second ES wave around the upper hybrid frequency. (2) From the middle of the foot all the way to the ramp, electrons can couple with both incident and reflected ions. ES waves excited by ECDI in different directions propagate across each other. Electromagnetic (EM) waves (X mode) emitted toward upstream are observed in both regions. They are probably induced by a small fraction of relativistic electrons. The impact of shock front rippling, Mach numbers, and dimensions on the ES wave excitation also will be discussed. Results shed new insight on the mechanism for the occurrence of ES wave excitations and possible EM wave emissions at young coronal mass ejection–driven shocks in the near-Sun solar wind.</span></p>

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