scholarly journals Evolution of an arched magnetized laboratory plasma in a sheared magnetic field

2021 ◽  
Vol 87 (6) ◽  
Author(s):  
Kamil D. Sklodowski ◽  
Shreekrishna Tripathi ◽  
Troy Carter
Keyword(s):  
Magnetic Field ◽  
Temporal Evolution ◽  
Electrical Current ◽  
Magnetized Plasma ◽  
Plasma Current ◽  
Laboratory Plasma ◽  
Parallel Orientation ◽  
Laboratory Plasmas ◽  
Plasma Radius ◽  
Spatio Temporal

Arched magnetized structures are a common occurrence in space and laboratory plasmas. Results from a laboratory experiment on spatio-temporal evolution of an arched magnetized plasma ( $\beta \approx 10^{-3}$ , Lundquist number $\approx 10^{4}$ , plasma radius/ion gyroradius $\approx 20$ ) in a sheared magnetic configuration are presented. The experiment is designed to model conditions relevant to the formation and destabilization of similar structures in the solar atmosphere. The magnitude of a nearly horizontal overlying magnetic field was varied to study its effects on the writhe and twist of the arched plasma. In addition, the direction of the guiding magnetic field along the arch was varied to investigate its role in the formation of either forward- or reverse-S shaped plasma structures. The electrical current in the arched plasma was well below the current required to make it kink unstable. A significant increase in the writhe of the arched plasma was observed with larger magnitudes of overlying magnetic field. A forward-S shaped arched plasma was observed for a guiding magnetic field oriented nearly antiparallel to the initial arched plasma current, while the parallel orientation yielded the reverse-S shaped arched plasma.

scholarly journals Laboratory simulation of solar magnetic flux rope eruptions

2010 ◽  
Vol 6 (S273) ◽  
pp. 483-486
Author(s):  
S. K. P. Tripathi ◽  
W. Gekelman
Keyword(s):  
Magnetic Flux ◽  
Flux Rope ◽  
Magnetized Plasma ◽  
Three Dimensions ◽  
Laboratory Simulation ◽  
Laboratory Plasma ◽  
Magnetic Flux Ropes ◽  
Solar Prominences ◽  
Plasma Experiment ◽  
Spatio Temporal

AbstractA laboratory plasma experiment has been constructed to simulate the eruption of arched magnetic flux ropes (AMFRs e.g., coronal loops, solar prominences) in an ambient magnetized plasma. The laboratory AMFR is produced using an annular hot LaB6 cathode and an annular anode in a vacuum chamber which has additional electrodes to produce the ambient magnetized plasma. Two laser beams strike movable carbon targets placed behind the annular electrodes to generate controlled plasma flows from the AMFR footpoints that drives the AMFR eruption. The experiment operates with a 0.5 Hz repetition rate and is highly reproducible. Thus, time evolution of the AMFR is recorded in three-dimensions with high spatio-temporal resolutions using movable diagnostic probes. Experimental results demonstrate outward expansion of the AMFR, release of its plasma to the background, and excitation of fast magnetosonic waves during the eruption.

scholarly journals Numerical simulation of Raman and Brillouin laser-pulse amplification in a magnetized plasma

2016 ◽  
Vol 34 (2) ◽  
pp. 315-337 ◽  
Author(s):  
Magdi Shoucri
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Distribution Functions ◽  
Magnetized Plasma ◽  
Numerical Code ◽  
Seed Pulse ◽  
Pulse Amplification ◽  
Laboratory Plasmas ◽  
Electrons And Ions ◽  
Amplification Process

AbstractWe apply an Eulerian Vlasov code to study the amplification of an ultra-short seed pulse via stimulated Raman and Brillouin backscattering of energy from a long pump pulse, assumed at constant amplitude, in a plasma embedded in an external magnetic field. Detailed analysis of the spectra developed during the amplification process are presented, together with the evolution showing the pump depletion, accompanied by the counter-propagating seed-pulse amplification, compression and increased steepness of the waveform. In addition to the problem of the amplification of ultra-short seed pulses, there is an obvious academic interest in the study of problems of amplification of electromagnetic waves observed in many situations in laboratory plasmas and in the magnetosphere and other geophysical situations, such as in the environments of planets, where important variations in the presence and strength of magnetic fields are observed. The numerical code solves a one-dimensional relativistic Vlasov–Maxwell set of equations for a plasma in a magnetic field for both electrons and ions. We also apply the code to the problem of wakefield acceleration. The absence of noise in the Eulerian Vlasov code allows one to follow the evolution of the system with an accurate representation of the phase-space structures of the distribution functions.

Collisional instability in a rare magnetized plasma: an experimental model for magnetospheric and space plasma study

2009 ◽  
Vol 75 (3) ◽  
pp. 395-406 ◽  
Author(s):  
CONSTANTINE L. XAPLANTERIS
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Theoretical Model ◽  
Low Frequency ◽  
Space Plasma ◽  
Magnetized Plasma ◽  
Laboratory Plasma ◽  
Geometrical Symmetry ◽  
Low Frequency Waves ◽  
Production Conditions

AbstractIn a suitable experimental device, laboratory plasma is produced with conditions and parameters analogous to magnetospheric plasma; we light a rare plasma in a semi-machine using rf-frequency discharge. Three ranges of low-frequency instabilities appear, one of which is identified as drift, caused by electron–neutral collisions. A full theoretical elaboration adapted to production conditions and geometrical symmetry is carried out; one solution of the dispersion relation is sufficient justification for the existence of the instability. The mathematical analysis also has the ambition to give interpretation for other low-frequency waves. Here we make a sound identification of the instability type as drift resistive due to electron–neutral collisions by an investigation of the growth rate. An agreement between experimental results and the theoretical model is obtained. As in the magnetosphere, an external magnetic field restrains the plasma.

Introduction of Zeeman splitting in CHIANTI

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
M. Giarrusso ◽  
E. Landi ◽  
G. Del Zanna ◽  
F. Leone
Keyword(s):  
Magnetic Field ◽  
Zeeman Splitting ◽  
Spectral Lines ◽  
Stokes Parameters ◽  
Atomic Data ◽  
Diagnostic Tools ◽  
Laboratory Plasma ◽  
Plasma Parameters ◽  
Laboratory Plasmas ◽  
New Feature

High-resolution spectra emitted by laboratory plasmas provide invaluable diagnostic tools for the measurement of plasma properties. To be implemented, they require a large amount of atomic data and transition rates, which are available in several spectral codes. In this paper we present a new feature added to the CHIANTI code, which allows us to calculate the Zeeman splitting of spectral lines in the presence of a magnetic field with known intensity and orientation. When combined with the CHIANTI database and software to calculate level populations and line emissivities, this new feature returns the emissivities in all four Stokes parameters, that can be utilized for the measurement of the magnetic field inside laboratory plasma chambers, along with other plasma parameters. This new feature can be applied to the analysis of the emission of laboratory plasmas created in different devices.

scholarly journals Temporal evolution of femtosecond laser filament detected via magnetic field around plasma current

2017 ◽  
Vol 25 (26) ◽  
pp. 32514 ◽  
Author(s):  
Shiyou Chen ◽  
Xiao-Long Liu ◽  
Xin Lu ◽  
Jinglong Ma ◽  
Jinguang Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Femtosecond Laser ◽  
Temporal Evolution ◽  
Plasma Current

Tuning the Magnetic Alignment of Cellulose Nanocrystals from Perpendicular to Parallel Using Lepidocrocite Nanoparticles

2019 ◽  
Author(s):  
Valentina Guccini ◽  
Sugam Kumar ◽  
Yulia Trushkina ◽  
Gergely Nagy ◽  
Christina Schütz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Cellulose Nanocrystals ◽  
Small Angle Neutron Scattering ◽  
Lower Amount ◽  
Magnetic Alignment ◽  
Polarized Optical Microscopy ◽  
Parallel Orientation ◽  
Weak Magnetic Fields

The magnetic alignment of cellulose nanocrystals (CNC) and lepidocrocite nanorods (LpN), pristine and in hybrid suspensions has been investigated using contrast-matched small-angle neutron scattering (SANS) under in situ magnetic fields (0 – 6.8 T) and polarized optical microscopy. The pristine CNC (diamagnetic) and pristine LpN (paramagnetic) align perpendicular and parallel to the direction of field, respectively. The alignment of both the nanoparticles in their hybrid suspensions depends on the relative amount of the two components (CNC and LpN) and strength of the applied magnetic field. In the presence of 10 wt% LpN and fields < 1.0 T, the CNC align parallel to the field. In the hybrid containing lower amount of LpN (1 wt%), the ordering of CNC is partially frustrated in all range of magnetic field. At the same time, the LpN shows both perpendicular and parallel orientation, in the presence of CNC. This study highlights that the natural perpendicular ordering of CNC can be switched to parallel by weak magnetic fields and the incorporation of paramagnetic nanoparticle as LpN, as well it gives a method to influence the orientation of LpN.<br>

Spatio-temporal evolution and dynamic origin of Jurassic-Cretaceous magmatism in the South China Block

2021 ◽  
Vol 217 ◽  
pp. 103605
Author(s):  
Xianzhi Cao ◽  
Nicolas Flament ◽  
Sanzhong Li ◽  
R. Dietmar Müller
Keyword(s):  
South China ◽  
Temporal Evolution ◽  
South China Block ◽  
The South ◽  
Spatio Temporal ◽  
Cretaceous Magmatism

scholarly journals Spatio-temporal evolution and influencing mechanism of the COVID-19 epidemic in Shandong province, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinlong Shi ◽  
Xing Gao ◽  
Shuyan Xue ◽  
Fengqing Li ◽  
Qifan Nie ◽  
...  
Keyword(s):  
Prevention And Control ◽  
Temporal Evolution ◽  
Geographical Location ◽  
Shandong Province ◽  
Control Measures ◽  
Middle Aged ◽  
Health Crisis ◽  
Aged People ◽  
Spatio Temporal ◽  
And Control

AbstractThe novel coronavirus pneumonia (COVID-19) outbreak that emerged in late 2019 has posed a severe threat to human health and social and economic development, and thus has become a major public health crisis affecting the world. The spread of COVID-19 in population and regions is a typical geographical process, which is worth discussing from the geographical perspective. This paper focuses on Shandong province, which has a high incidence, though the first Chinese confirmed case was reported from Hubei province. Based on the data of reported confirmed cases and the detailed information of cases collected manually, we used text analysis, mathematical statistics and spatial analysis to reveal the demographic characteristics of confirmed cases and the spatio-temporal evolution process of the epidemic, and to explore the comprehensive mechanism of epidemic evolution and prevention and control. The results show that: (1) the incidence rate of COVID-19 in Shandong is 0.76/100,000. The majority of confirmed cases are old and middle-aged people who are infected by the intra-province diffusion, followed by young and middle-aged people who are infected outside the province. (2) Up to February 5, the number of daily confirmed cases shows a trend of “rapid increase before slowing down”, among which, the changes of age and gender are closely related to population migration, epidemic characteristics and intervention measures. (3) Affected by the regional economy and population, the spatial distribution of the confirmed cases is obviously unbalanced, with the cluster pattern of “high–low” and “low–high”. (4) The evolution of the migration pattern, affected by the geographical location of Wuhan and Chinese traditional culture, is dominated by “cross-provincial” and “intra-provincial” direct flow, and generally shows the trend of “southwest → northeast”. Finally, combined with the targeted countermeasures of “source-flow-sink”, the comprehensive mechanism of COVID-19 epidemic evolution and prevention and control in Shandong is revealed. External and internal prevention and control measures are also figured out.

Sign in / Sign up

Export Citation Format

Share Document