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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.

 

번호 일시 장소 연사 제목
공지 2019/09/18 - 12/5  Seminar Room #1323  Prof. David Schuster and etc.  Fall 2019: Physics Seminar Serises
공지 2019/09/02 - 12/09  Seminar Room 1501  이호성 박사 (한국표준과학연구원) and etc.  Fall 2019: Physics Colloquium
194 January 17 (Fri), 4:00 PM  #1323, E6-2  Hiroki Ikegami  Symmetry Breaking and Topology in Superfluid 3He file
193 February 20 (Thu), 4:00 PM  #1323, E6-2  Seunghyun Khim  Unconventional superconductivity in the locally non-centrosymmetric heavy-fermion CeRh2As2 file
192 Oct. 17th (Mon) 11:00 AM  #1323,(E6-2, 1st fl.)  Nguyen Quang Liem, Institute of Materials Science, VAST, Viettnam  IMS and examples of the studies on optoelectronic materials
191 Apr. 28 (Thu.) 3PM  #2501(E6-2. 2nd fl.)  Dr. Chang Hee Sohn, SEOUL NATIONAL UNIVERSITY  Lattice/Spin/Charge Coupling in 5d Pyrochlore Cd2Os2O7
190 December 13 (Fri.), 1:00 PM  #2501, E6-2  Dr. Chang-Jong Kang  Computational Material Designs: Current Status and Future Directions file
189 April 6 (Fri.), 10:00 AM  #2502, E6  박채연 박사  Entanglement and thermalization in many-body systems: recent progress file
188 June 27 (Thu), 2:00 PM  #2502, E6-2  Hyun-Yong Lee  Gapless Kitaev Spin Liquid to Loop and String Gases file
187 Sep10(Tue), 15:00  #2502, E6-2  Jun Ho Son  (2+1) D Duality Web from 3D Euclidean Lattice file
186 November 20 (Wed.), 4:00 PM  #5302, E6-2  Dr. Shigeyuki Ishida  Correlation between superconducting transition temperature and critical current density in irradiated iron-based superconductors file
185 February 21 (Thu.), 16:00 PM  #5313, E6-2  Prof. Diptimoy Ghosh  B-meson charged current anomalies - Theoretical status file
184 Nov. 8 (Wed.), 1:00 PM  #5318 (E6-2. 5th fl.)  Prof. Y. Matsuda Department of Physics, Kyoto University  “Emergent exotic quasiparticles in quantum spin liquids” file
183 Nov. 18th (Fri) 10:30 a.m.  #5318(5th fl.)  Dr. 최 순 원, Havard University  Non-equilibrium many-body spin dynamics in diamond
182 AUG. 31 (Thu.), 2 PM  #5318(E6-2. 5th fl.)  Prof. Hiroaki Ishizuka (The University of Tokyo)  “Berry phase and nonlinear response: photocurrent in noncentrosymmetric insulators and Weyl semimetals” file
181 May 21 (Tue.), 4:00 PM  #5318, E6-2  임준원 박사  Classification of flat bands according to the band-crossing singularity of Bloch wave functions file
180 Dec 27 (Fri), 3:00 PM  #5318, E6-2  Han Gyeol Suh  The superconducting order parameter puzzle of Sr2RuO4 file
179 Feb. 12 (Mon), 3:00pm  #C303, (Creation Hall 3F, KAIST Munji Campus)  Dr. Byeongsu Yang, Kamioka Observatory, Univ. of Tokyo  The recent result of XMASS Experiment
178 2015/03/04, 12PM  1323호, E6-2  Prof. Choi Hak-Soo(Harvard)  Bioimaging and Biosensing Using Near-Infrared Fluorescence file
177 Dec. 12th (Mon)  1:30p.m. #1323(E6-2. 1st fl.)  Dongjoon Song , AIST  “Possible symmetry in the phase diagrams of electron- & hole-doped cuprate high-Tc superconductors”
176 Oct. 18 (Tue.), 1:30 PM  1st fl. #1323(E6-2)  Dr. Chan-Ho Yang, Department of Physics, KAIST  "Visualization of oxygen vacancy in motion and the interplay with electronic conduction"