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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
189 Nov. 11th(Fri), 1:30 p.m.  #1323(E6-2. 1st fl.)  Dr. Keun Su Kim, POSTECH  Bandgap Engineering of Black Phosphorus
188 Apr. 01 (Fri.) 2:30 PM  E6-2. 1st fl. #1501  Dr. KICHEON KANG, Chonnam National University  Interference of single charged particles without a loop and dynamic nonlocality
187 May 31 (Tue.) 4 PM  #1323(E6-2, 1st fl.)  Dr. Kimin Kim, KAIST  Understanding 3D tokamak physics towards advanced control of toroidal plasma
186 May. 11 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Kun Woo Kim  Disordered Floquet topological insulators file
185 Dec. 9(Fri), 4p.m.  #1323(E6-2. 1st fl.  Dr. Kun Woo Kim, KIAS  Shift Charge and Spin Photocurrents in Dirac Surface States of Topological Insulator
184 2015/12/11, 1:30PM  E6-2, #1323  Dr. KwangYong Choi  (Chung-Ang University)  Quantum spin liquid in the 1/3 depleted triangular lattice Ba3(Ru1-xIrx)Ti2O9
183 2016/03/11 1:30 PM  E6-2. 1st fl. #1501  Dr. Kwon Park  Topological phases of matter in nonequilibrium: Topology of the Wannier-Stark ladder
182 November 1 (Thu.), 16:00 PM  #1323, E6-2  Dr. KyeoReh Lee  Direct holography from a single snapshot file
181 2015/07/16, 4PM  E6-2, 1318  Dr. Kyunghan Hong(MIT)  Next-generation ultrafast laser technology for nonlinear optics and strong-field physics
180 October 26 (Fri.), 4:00 PM  #1323, E6-2  Dr. Kyusung Hwang  Coexisting triple-point and nodal-line topological magnons and thermal Hall effect in pyrochlore iridates file
179 Mar. 24 (Fri.), 2:30 PM  #1323 (1st fl. E6-2).  Dr. MahnSoo Choi  Topological Dynamics
178 2015/10/15, 10AM  E6-2, 5th fl. #5318  Dr. Mark D. Bird (Florida State University)  Development of Large-Bore, High Field Magnets at the NHMFL
177 May 19, 2016 (Thur.) 3PM  May 19, 2016 (Thur.) 3PM,  Dr. Michael Betz, CERN  The CERN Resonant WISP Search: Development, Results and Lesson-Learned
176 Jul. 08 (Fri.) 11:00 AM  #1323(E6-2. 1st fl.)  Dr. Michael Lawler(Binghampton Univ. / Cornell Univ.)  Isostatic magnetism
175 2015/11/23, 1:30PM  E6-2, #1323  Dr. Michael Park (Stanford University)  What's Beyond the Standard Model? Lessons from Run I and what might come in Run II
174 Feb. 1 (Wed.), 2p.m.  #1323(E6-2. 1st fl.)  Dr. Michihisa Yamamoto, Department of Applied Physics, The University of Tokyo  Quantum electron optics using flying electrons
173 Sep. 10 (Tue.), 03:00 PM  E6-2. 1st fl. #1323  Dr. Mikhail Kiselev  Two-Stage Kondo Effect file
172 Nov. 3 (Fri.), 2:30 PM  #1323 (1st fl., E6-2.)  Dr. MinChul Lee(Department of Applied Physics, Kyung Hee Univ.)  Quantum Resistor-Capacitor Circuit with Majorana Edge States file
171 July 30 (Tue), 4:00 PM  #1323, E6-2  Dr. Mingu Kang  Dirac fermions and flat bands in correlated kagome metals file
170 Apr. 28 (Fri.), 04:00 PM  #1323 (E6-2. 1st fl.)  Dr. Minkyung Jung Research Institute, DGIST  Carbon nanotubes coupled to superconducting impedance matching circuits