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장소 #1323(E6-2 1st fl.) 
일시 Jun 1 (Wed) 4 PM 
연사 Kil-Byoung Chai, Caltech 

Laboratory experiments relevant to mesospheric clouds, Saturn’s rings & astrophysical jets

 

Jun 1 (Wed) 4 PM, #1323(E6-2 1st fl.)
Kil-Byoung Chai, Caltech

 

An rf discharge with liquid nitrogen cooled electrodes and injected water vapor has been used to study nucleation, growth, and dynamics of water-ice grains spontaneously formed in a plasma environment. Examples of water-ice dusty plasmas include polar mesospheric clouds, Saturn’s diffusive rings, and protoplanetary disks. We found that fast grain growth to nonspherical shape with up to 5:1 elongation occurs when the water molecule mean free path exceeds the ice grain screening length. Ice grains grow largest in light gas plasmas, up to 500 µm long in hydrogen plasma. Elongated ice grains align along the plasma ambipolar electric field. Microscope images reveal that the ice grains have fractal nature with 1.7 typical fractal dimension. After the growth process ends, poloidal vortex motion of ice grains is observed and is shown to result from the non-conservative ion drag force.

The Caltech jet experiment produces low beta, high Lundquist number, high density (~1022 m-3) MHD-driven plasma jets and so is similar to astrophysical jets and solar corona loops. We have recently studied various phenomena associated with magnetic reconnection induced by a kink-driven Rayleigh-Taylor instability using comprehensive diagnostics. The results of this study include the following: A spatially localized EUV burst is imaged at the presumed position of fast magnetic reconnection in a plasma jet; the existence of this localized EUV burst indicates strong localized electron heating. Circularly polarized high frequency whistler waves are simultaneously observed indicating that Hall dynamics likely governs the reconnection. Spectroscopic measurement shows simultaneous fast ion heating. We propose that the electron heating is consistent with Ohmic dissipation while the ion heating is consistent with ion trajectories becoming stochastic.

 

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250 MAR. 26 (TUE), 0300 PM  E6-2. 2st fl. #2501  Prof. Jung Hoon Han  Consideration of thermal Hall effect in frustrated and un-frustrated quantum magnets file
249 Mar. 25(Fri.) 11:00  E6-1 #1323  Prof. Ara Go (Department of Physics, Chonnam National University)  (응집물리 세미나) Hund's metallicity in ruthenate systems file
248 Mar. 24 (Fri.), 4:00 PM  #1323 (1st fl. E6-2)  Dr. SangWook Lee  Graphene based nano electronics and nano electromechanics; focusing on precise control of nano structures for studying accurate physical properties
247 Mar. 24 (Fri.), 2:30 PM  #1323 (1st fl. E6-2).  Dr. MahnSoo Choi  Topological Dynamics
246 Mar. 16 (Fri.), 04:0 PM  E6-2. 1st fl. #1323  Dr. YoungDuck Kim  Van der Waals Heterostructures from Quantum Transport to Ultrafast Optoelectronics file
245 Mar. 16 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. JinHee Kim  산화물 다층박막에서의 다양한 물리현상 file
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243 June 4 (Tue.), 5:00 PM  #1323, E6-2  Prof. Minsu Kim  Stochastic nature of bacterial eradication using antibiotics file
242 June 3rd, Fri. 9:30 AM  Online seminar  Prof. Juejun Hu ( Massachusetts Institute of Technology)  (Quantum-&Nano-Photonics Webinar) Seeing glass in a new light: reimagine chalcogenide photonics file
241 June 3(Fri.) 11:00  E6-2 #1323  Prof. Gil Young Cho (Department of Physics, POSTECH)  (응집물리 세미나) Theoretical Investigation of Exotic Quantum States in Low-dimensional Materials
240 June 28 (Fri.), 13:30 PM  #1323, E6-2  Dr. Yusuke Kozuka  Magnetic domains and domain wall conduction in pyrochlore iridate thin films and heterostructures file
239 June 27 (Wed.), 13:30 PM  #1323, E6-2  Dr. Jung Sik Park  Magnetic reversal of artificial spin ice file
238 June 27 (Thu), 2:00 PM  #2502, E6-2  Hyun-Yong Lee  Gapless Kitaev Spin Liquid to Loop and String Gases file
237 June 23th (Thur), 11:00  E6 Room(#1322)  Sun Yool Park(Joint Institute for Laboratory Astrophysics (JILA) & University of Colorado)  JILA’s search for the electron’s Electric Dipole Moment (eEDM) to probe physics beyond the standard model file
236 June 22 (Fri.), 04:00 PM  #1323, E6-2  Dr. Daniel Sando  Tuning functional properties of BiFeO3 films using strain and growth chemistry file
235 June 22 (Fri.), 04:00 PM  #1323, E6-2  Dr. Daniel Sando  Tuning functional properties of BiFeO3 films using strain and growth chemistry file
234 June 17 (Mon.), 10:30 AM  #1323, E6-2  Dr. See-Hun Yang  Chiral Spintronics file
233 June 14, 2016 (Tue) 3PM  #1323 (E6-2 1st fl.)  Prof. Seungyong Hahn, Florida State University  No-Insulation High Temperature Superconductor Magnet Technology for Compact, Reliable, and Low-Cost High Field DC Magnets