50057
2019
2019
eng
9
3
5
article
American Assoc. for the Advancement of Science
Washington
1
--
2019-01-28
--
The birth of a coronal mass ejection
The Sun’s atmosphere is frequently disrupted by coronal mass ejections (CMEs), coupled with flares and energetic particles. The coupling is usually attributed to magnetic reconnection at a vertical current sheet connecting the flare and CME, with the latter embedding a helical magnetic structure known as flux rope. However, both the origin of flux ropes and their nascent paths toward eruption remain elusive. Here, we present an observation of how a stellar-sized CME bubble evolves continuously from plasmoids, mini flux ropes that are barely resolved, within half an hour. The eruption initiates when plasmoids springing from a vertical current sheet merge into a leading plasmoid, which rises at increasing speeds and expands impulsively into the CME bubble, producing hard x-ray bursts simultaneously. This observation illuminates a complete CME evolutionary path capable of accommodating a wide variety of plasma phenomena by bridging the gap between microscale and macroscale dynamics.
Science Advances
10.1126/sciadv.aau7004
30906858
2375-2548
wos:2019
eaau7004
WOS:000462564300023
Liu, R (reprint author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Anhui, Peoples R China.; Liu, R (reprint author), CAS Ctr Excellence Comparat Planetol, Hefei 230026, Anhui, Peoples R China.; Kliem, B (reprint author), Univ Potsdam, Inst Phys & Astron, D-14476 Potsdam, Germany.; Kliem, B (reprint author), Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England., rliu@ustc.edu.cn; bkliem@uni-potsdam.de
NSFCNational Natural Science Foundation of China [41474151, 41774150, 41761134088, 41774178, 41574165, KL 817/8-1/NSFC, 41421063]; Thousand Young Talents Program of China; DFGGerman Research Foundation (DFG); NASANational Aeronautics & Space Administration (NASA) [NNX16AH87G, 80NSSC17K0016]; Austrian Science Fund (FWF)Austrian Science Fund (FWF) [P27292-N20]; CAS Key Research Program of Frontier Sciences [QYZDB-SSW-DQC015]; fundamental research funds for the central universitiesFundamental Research Funds for the Central Universities
2021-03-23T13:47:39+00:00
sword
importub
filename=package.tar
585dad7db5b8577ac44c4836157bf6cb
Liu, Rui
Kliem, Bernhard
false
true
CC-BY-NC - Namensnennung, nicht kommerziell 4.0 International
Tingyu Gou
Rui Liu
Bernhard Kliem
Yuming Wang
Astrid M. Veronig
Physik
Institut für Physik und Astronomie
Referiert
Import
Gold Open-Access
DOAJ gelistet
34802
2013
2013
eng
13
2
773
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Observation of a moretown wave and wave-filament interactions associated with the renowned X9 flare on 1990 May 24
Using Big Bear Solar Observatory film data recently digitized at NJIT, we investigate a Moreton wave associated with an X9 flare on 1990 May 24, as well as its interactions with four filaments F1-F4 located close to the flaring region. The interaction yields interesting insight into physical properties of both the wave and the filaments. The first clear Moreton wavefront appears at the flaring-region periphery at approximately the same time as the peak of a microwave burst and the first of two gamma-ray peaks. The wavefront propagates at different speeds ranging from 1500-2600 km s(-1) in different directions, reaching as far as 600 Mm away from the flaring site. Sequential chromospheric brightenings are observed ahead of the Moreton wavefront. A slower diffuse front at 300-600 km s(-1) is observed to trail the fast Moreton wavefront about one minute after the onset. The Moreton wave decelerates to similar to 550 km s(-1) as it sweeps through F1. The wave passage results in F1's oscillation which is featured by similar to 1 mHz signals with coherent Fourier phases over the filament, the activation of F3 and F4 followed by gradual recovery, but no disturbance in F2. Different height and magnetic environment together may account for the distinct responses of the filaments to the wave passage. The wavefront bulges at F4, whose spine is oriented perpendicular to the upcoming wavefront. The deformation of the wavefront is suggested to be due to both the forward inclination of the wavefront and the enhancement of the local Alfven speed within the filament channel.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/773/2/166
0004-637X
wos:2011-2013
166
WOS:000323426100085
Liu, R (reprint author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China., rliu@ustc.edu.cn
NSF [AGS 0839216, AGS 0849453, AGS-1153226, AGS-1153424]; Thousand Young
Talents Program of China; NSFC [41222031, 41131065, 41121003]; 973 key
project [2011CB811403]; CAS [KZZD-EW-01-4]; fundamental research funds
for the central universities [WK2080000031]; DFG; STFC; Chinese Academy
of Sciences [2012T1J0017]
Rui Liu
Chang Liu
Yan Xu
Wei Liu
Bernhard Kliem
Haimin Wang
eng
uncontrolled
Sun: filaments, prominences
eng
uncontrolled
Sun: flares
eng
uncontrolled
Sun: oscillations
eng
uncontrolled
waves
Institut für Physik und Astronomie
Referiert
37556
2014
2014
eng
10
2
792
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Slow rise and partial eruption of a double-decker filament. II. A double flux rope model
Force-free equilibria containing two vertically arranged magnetic flux ropes of like chirality and current direction are considered as a model for split filaments/prominences and filament-sigmoid systems. Such equilibria are constructed analytically through an extension of the methods developed in Titov & Demoulin and numerically through an evolutionary sequence including shear flows, flux emergence, and flux cancellation in the photospheric boundary. It is demonstrated that the analytical equilibria are stable if an external toroidal (shear) field component exceeding a threshold value is included. If this component decreases sufficiently, then both flux ropes turn unstable for conditions typical of solar active regions, with the lower rope typically becoming unstable first. Either both flux ropes erupt upward, or only the upper rope erupts while the lower rope reconnects with the ambient flux low in the corona and is destroyed. However, for shear field strengths staying somewhat above the threshold value, the configuration also admits evolutions which lead to partial eruptions with only the upper flux rope becoming unstable and the lower one remaining in place. This can be triggered by a transfer of flux and current from the lower to the upper rope, as suggested by the observations of a split filament in Paper I. It can also result from tether-cutting reconnection with the ambient flux at the X-type structure between the flux ropes, which similarly influences their stability properties in opposite ways. This is demonstrated for the numerically constructed equilibrium.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/792/2/107
0004-637X
1538-4357
wos:2014
107
WOS:000341172200025
Kliem, B (reprint author), Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24, D-14476 Potsdam, Germany., bkliem@uni-potsdam.de
DFG; STFC; NSF [AGS-1249270, AGS-1153226, AGS-1348513]; Chinese Academy
Science and Technology Center); NASA [NNX13AG13G, NNX13AF76G]
Bernhard Kliem
Tibor Toeroek
Viacheslav S. Titov
Roberto Lionello
Jon A. Linker
Rui Liu
Chang Liu
Haimin Wang
eng
uncontrolled
instabilities
eng
uncontrolled
magnetohydrodynamics (MHD)
eng
uncontrolled
Sun: coronal mass ejections (CMEs)
eng
uncontrolled
Sun: filaments, prominences
eng
uncontrolled
Sun: flares
Institut für Physik und Astronomie
Referiert
35667
2012
2012
eng
14
1
756
article
IOP Publ. Ltd.
Bristol
1
--
--
--
Slow rise and partial eruption of a double-decker filament. I. observations and interpretation
We study an active-region dextral filament that was composed of two branches separated in height by about 13 Mm, as inferred from three-dimensional reconstruction by combining SDO and STEREO-B observations. This "double-decker" configuration sustained for days before the upper branch erupted with a GOES-class M1.0 flare on 2010 August 7. Analyzing this evolution, we obtain the following main results. (1) During the hours before the eruption, filament threads within the lower branch were observed to intermittently brighten up, lift upward, and then merge with the upper branch. The merging process contributed magnetic flux and current to the upper branch, resulting in its quasi-static ascent. (2) This transfer might serve as the key mechanism for the upper branch to lose equilibrium by reaching the limiting flux that can be stably held down by the overlying field or by reaching the threshold of the torus instability. (3) The erupting branch first straightened from a reverse S shape that followed the polarity inversion line and then writhed into a forward S shape. This shows a transfer of left-handed helicity in a sequence of writhe-twist-writhe. The fact that the initial writhe is converted into the twist of the flux rope excludes the helical kink instability as the trigger process of the eruption, but supports the occurrence of the instability in the main phase, which is indeed indicated by the very strong writhing motion. (4) A hard X-ray sigmoid, likely of coronal origin, formed in the gap between the two original filament branches in the impulsive phase of the associated flare. This supports a model of transient sigmoids forming in the vertical flare current sheet. (5) Left-handed magnetic helicity is inferred for both branches of the dextral filament. (6) Two types of force-free magnetic configurations are compatible with the data, a double flux rope equilibrium and a single flux rope situated above a loop arcade.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.1088/0004-637X/756/1/59
0004-637X
wos:2011-2013
59
WOS:000309044300059
Liu, R (reprint author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China., rui.liu@njit.edu
Thousand Young Talents Program of China; NSFC [41131065, 41121003]; 973
key project [2011CB811403]; CAS Key Research Program [KZZD-EW-01-4];
fundamental research funds for the central universities [WK2080000031];
NASA [NNX08-AJ23G, NNX08-AQ90G]; NSF [ATM-0849453, ATM-0819662]; DFG;
STFC; NASA's HTP program; NASA's LWS program; NASA's SRT program; CISM
(an NSF Science and Technology Center); Key Laboratory of Solar
Activity, National Astronomical Observatories of Chinese Academy of
Sciences [KLSA201201]
Rui Liu
Bernhard Kliem
Tibor Toeroek
Chang Liu
Viacheslav S. Titov
Roberto Lionello
Jon A. Linker
Haimin Wang
eng
uncontrolled
Sun: coronal mass ejections (CMEs)
eng
uncontrolled
Sun: filaments, prominences
eng
uncontrolled
Sun: flares
Institut für Physik und Astronomie
Referiert
45603
2016
2016
eng
22
818
article
IOP Publ. Ltd.
Bristol
1
--
--
--
STRUCTURE, STABILITY, AND EVOLUTION OF MAGNETIC FLUX ROPES FROM THE PERSPECTIVE OF MAGNETIC TWIST
We investigate the evolution of NOAA Active Region (AR) 11817 during 2013 August 10–12, when it developed a complex field configuration and produced four confined, followed by two eruptive, flares. These C-and-above flares are all associated with a magnetic flux rope (MFR) located along the major polarity inversion line, where shearing and converging photospheric flows are present. Aided by the nonlinear force-free field modeling, we identify the MFR through mapping magnetic connectivities and computing the twist number ${{ \mathcal T }}_{w}$ for each individual field line. The MFR is moderately twisted ($| {{ \mathcal T }}_{w}| \lt 2$) and has a well-defined boundary of high squashing factor Q. We found that the field line with the extremum $| {{ \mathcal T }}_{w}| $ is a reliable proxy of the rope axis, and that the MFR's peak $| {{ \mathcal T }}_{w}| $ temporarily increases within half an hour before each flare while it decreases after the flare peak for both confined and eruptive flares. This pre-flare increase in $| {{ \mathcal T }}_{w}| $ has little effect on the AR's free magnetic energy or any other parameters derived for the whole region, due to its moderate amount and the MFR's relatively small volume, while its decrease after flares is clearly associated with the stepwise decrease in the whole region's free magnetic energy due to the flare. We suggest that ${{ \mathcal T }}_{w}$ may serve as a useful parameter in forewarning the onset of eruption, and therefore, the consequent space weather effects. The helical kink instability is identified as the prime candidate onset mechanism for the considered flares.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.3847/0004-637X/818/2/148
0004-637X
1538-4357
wos2016:2019
148
WOS:000372302800047
Liu, R (reprint author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China.; Liu, R (reprint author), Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei 230026, Peoples R China., rliu@ustc.edu.cn
Thousand Young Talents Program of China, NSFC [41222031, 41474151]; NSFC [41131065]; CAS [KZZD-EW-01-4, 2012T1J0017]; fundamental research funds for the central universities; DFG; NSF SHINE program; NSF [AGS 1348513, 1408703]; NASA [NNX13AG13G, NNX13AF76G]
importub
2020-03-22T19:55:01+00:00
filename=package.tar
c286dd75d0f30aecbb7b257750b890ab
Rui Liu
Bernhard Kliem
Viacheslav S. Titov
Jun Chen
Yuming Wang
Haimin Wang
Chang Liu
Yan Xu
Thomas Wiegelmann
eng
uncontrolled
coronal mass ejections (CMEs)
eng
uncontrolled
Sun: corona
eng
uncontrolled
Sun: filaments, pominences
eng
uncontrolled
Sun: flares
eng
uncontrolled
Sun: magnetic fields
Institut für Physik und Astronomie
Referiert
Import
60144
2019
2020
eng
10
2
890
article
Institute of Physics Publ.
London
1
2020-02-25
2020-02-25
--
Extreme-ultraviolet late phase of solar flares
A second peak in the extreme ultraviolet sometimes appears during the gradual phase of solar flares, which is known as the EUV late phase (ELP). Stereotypically ELP is associated with two separated sets of flaring loops with distinct sizes, and it has been debated whether ELP is caused by additional heating or extended plasma cooling in the longer loop system. Here we carry out a survey of 55 M-and-above GOES-class flares with ELP during 2010-2014. Based on the flare-ribbon morphology, these flares are categorized as circular-ribbon (19 events), two-ribbon (23 events), and complex-ribbon (13 events) flares. Among them, 22 events (40%) are associated with coronal mass ejections, while the rest are confined. An extreme ELP, with the late-phase peak exceeding the main-phase peak, is found in 48% of two-ribbon flares, 37% of circular-ribbon flares, and 31% of complex-ribbon flares, suggesting that additional heating is more likely present during ELP in two-ribbon than in circular-ribbon flares. Overall, cooling may be the dominant factor causing the delay of the ELP peak relative to the main-phase peak, because the loop system responsible for the ELP emission is generally larger than, and well separated from, that responsible for the main-phase emission. All but one of the circular-ribbon flares can be well explained by a composite "dome-plate" quasi-separatrix layer (QSL). Only half of these show a magnetic null point, with its fan and spine embedded in the dome and plate, respectively. The dome-plate QSL, therefore, is a general and robust structure characterizing circular-ribbon flares.
The astrophysical journal : an international review of spectroscopy and astronomical physics
10.3847/1538-4357/ab6def
0004-637X
1538-4357
outputup:dataSource:WoS:2020
158
WOS:000629751100067
Liu, Rui (corresponding author), Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Anhui, Peoples R China.; Liu, R (corresponding author), CAS Ctr Excellence Comparat Planetol, Hefei 230026, Anhui, Peoples R China., rliu@ustc.edu.cn
NSFC-DFG [NSFC 41761134088, KL 817/8-1]; NSFC National Natural Science; Foundation of China (NSFC) [41774150, 11925302, 41421063]; CASChinese; Academy of Sciences [KZZD-EW-01-4]; fundamental research funds for the; central universitiesFundamental Research Funds for the Central; Universities; China Scholarship CouncilChina Scholarship Council; [201706340140]
Liu, Rui
2023-07-27T05:41:58+00:00
sword
importub
filename=package.tar
9d83eb8ab1c3c5950c882c9c26ef5847
1473835-1
false
true
Jun Chen
Rui Liu
Kai Liu
Arun Kumar Awasthi
Peijin Zhang
Yuming Wang
Bernhard Kliem
Astronomie und zugeordnete Wissenschaften
Institut für Physik und Astronomie
Referiert
Import
52394
2018
2018
eng
24
32
9
87
article
Elsevier
Oxford
1
2018-06-06
2018-06-06
--
Modeling and analysis of single-event transient sensitivity of a 65 nm clock tree
The soft error rate (SER) due to heavy-ion irradiation of a clock tree is investigated in this paper. A method for clock tree SER prediction is developed, which employs a dedicated soft error analysis tool to characterize the single-event transient (SET) sensitivities of clock inverters and other commercial tools to calculate the SER through fault-injection simulations. A test circuit including a flip-flop chain and clock tree in a 65 nm CMOS technology is developed through the automatic ASIC design flow. This circuit is analyzed with the developed method to calculate its clock tree SER. In addition, this circuit is implemented in a 65 nm test chip and irradiated by heavy ions to measure its SER resulting from the SETs in the clock tree. The experimental and calculation results of this case study present good correlation, which verifies the effectiveness of the developed method.
Microelectronics reliability
10.1016/j.microrel.2018.05.016
0026-2714
wos:2018
WOS:000441856500003
Li, YQ (reprint author), Univ Saskatchewan, Saskatoon, SK, Canada.; Li, YQ (reprint author), IHP, Frankfurt, Oder, Germany., li@ihp-microelectronics.com; lic900@mail.usask.ca; issam.nofal@iroctech.com
Natural Sciences and Engineering Research Council of Canada (NSERC)Natural Sciences and Engineering Research Council of Canada; CMC Microsystems
2021-10-27T08:47:30+00:00
sword
importub
filename=package.tar
4ce15c74f5bc667911d830ef82799cfd
Li, Yuanqing
false
true
Yuanqing Li
Li Chen
Issam Nofal
Mo Chen
Haibin Wang
Rui Liu
Qingyu Chen
Miloš Krstić
Shuting Shi
Gang Guo
Sang H. Baeg
Shi-Jie Wen
Richard Wong
eng
uncontrolled
Clock tree
eng
uncontrolled
Modeling
eng
uncontrolled
Single-event transient (SET)
Technik, Technologie
Institut für Informatik und Computational Science
Import