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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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241 Jun. 2 (Fri.), 4:00 PM  #1323 (E6-2. 1st fl.)  Dr. Sang Wook Kim  Maxwell's demon in quantum wonderland file
240 Jun. 2 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Euyheon Hwang(황의헌)  Quasiparticle Interference and Fourier transform scanning tunneling spectroscopy in WTe2 (Weyl semimetal) file
239 Jun. 18 (MON), 10:00 AM  E6-2. 2nd fl. #2502  Dr. Thibault VOGT  Rydberg electromagnetically induced transparency and microwave-to-optical conversion using Rydberg atoms file
238 Jun. 16 (Thu) 4PM  #1323(E6-2, 1st fl.)  Hyochul Kim, Samsung Advanced Institute of Technology  Quantum information processing using quantum dots and photonic crystal cavities
237 Jun. 14 (Tue) 4PM  Seminar Room (#2502, 2nd fl.)  Young-Sik Ra, Université Pierre et Marie Curie  Photonic quantum network based on multimode squeezed vacuums and single-photon subtraction
236 Jun. 11 (Fri.), 04:00 PM  Online seminar  Dr. Keun Su Kim(Yonsei University)  Pseudogap in surface-doped black phosphorus file
235 Jun. 11 (Fri.), 02:30 PM  Online seminar  Dr. Jin Woong Cha(KRISS)  Engineering sound waves and vibrations in multi-mode nanomechanical systems file
234 Jun. 10 (Fri.), 11:00 AM  Online seminar  Dr. Yoon Jang Chung(Laboratory for Physical Sciences, University of Maryland)  Record-quality two-dimensional electron systems file
233 Jun. 10 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Sanghoon Kim(Department of Physics, University of Ulsan)  Fe5GeTe2의 나선형 자성특성과 자기저항의 전류밀도 의존성 연구 file
232 Jun. 10 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Seunghun Lee(Department of Physics, Pukyong National University)  Combinatorial strategy for condensed matter physics: study on rare earth hexaborides thin films file
231 Jun. 1(Wed) 10:30 AM  BK21 Conference Room (#1318, E6-2)  Dr. Noriaki Horiuchi, Editor, Nature Photonics  Welcome to Nature Photonics
230 Jun. 01 (Fri.), 11:00 AM  E6-2. 1st fl. #1323  Dr. Seung Sae Hong  Topological phases in low-dimensional quantum materials file
229 Jun 8 (Tue), 10:00 AM  Zoom webinar  Toshihiko Baba (Yokohama National University, Japan)  Photonic crystal devices for sensing file
228 Jun 28, 14:00  E6-2, #1322  Dr. Bongjae Kim, Dr. Sooran Kim, Dr. Jeongwoon Hwang  1st Research-exchange meeting of computational material physics file
227 Jun 24 (Mon) 11:00  E6-2, #1323  Dr. Henning Schomerus  Topological photonic anomalies file
226 Jun 22(Tue) 17:00  Zoom webinar  Wei Han (Peking University, China)  Spintronics meets Quantum Materials file
» Jun 1 (Wed) 4 PM  #1323(E6-2 1st fl.)  Kil-Byoung Chai, Caltech  Laboratory experiments relevant to mesospheric clouds, Saturn’s rings & astrophysical jets
224 July. 14 (Fri.), 3:00 PM  #1323 (E6-2. 1st fl.)  Dr. Jun Hyun Lee / University of Maryland  Chiral anomaly in disordered Weyl semimetals file
223 July 9 (Mon.), 14:00 PM  #1323, E6-2  Prof. Cesar A. Hidalgo, MediaLab, MIT  The principles of collective learning file