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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
105 Nov. 1 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Ju-Jin Kim  Electron transport through weak-bonded contact metal with low dimensional nano-material file
104 Mar. 29 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Taeyoung Choi  Coherent Quantum Control and Magnetism on atoms – Trapped ion and ESR STM file
103 Nov. 1 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. YoungWook Kim  Squeezing the best out of 2D materials file
102 DEC. 27 (Thu), 04:00 PM  E6-2. 1st fl. #1323  Prof. Na Young Kim  Quantum Innovation (QuIN) Laboratory file
101 Apr. 12 (Tue.), 4 PM  E6-2. 1st fl. #1323  Dr. Jeehoon Kim, POSTECH  Confinement of Superconducting Vortices in Magnetic Force Microscopy
100 Mar. 16 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. JinHee Kim  산화물 다층박막에서의 다양한 물리현상 file
99 Apr. 28 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. JeongYoung Park Graduate School of EEWS, KAIST  Hot electron generation at surfaces and its impact to catalysis and renewable energy conversion
98 DEC. 11 (Tue), 04:00 PM  E6-2. 1st fl. #1323  Prof. Hiroshi Shinaoka  Natural compact representation of Matsubara Green’s functions: applications to analytic continuation and quantum many-body simulations file
97 Oct. 18 (Tue.), 3PM  E6-2. 1st fl. #1323  Dr. JunHo Suh, Korea Research Institute of Standards and Science  “Hybrid quantum systems with mechanical oscillators”
96 Nov. 9 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. Donghun Lee  Quantum sensing and imaging with diamond defect centers for nano-scale spin physics file
95 Jun. 01 (Fri.), 11:00 AM  E6-2. 1st fl. #1323  Dr. Seung Sae Hong  Topological phases in low-dimensional quantum materials file
94 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
93 Sep. 22 (Fri.), 04:00 PM  E6-2. 1st fl. #1323  Dr. GilHo Lee / Department of Physics, POSTECH  Unexpected Electron-Pairing in Integer Quantum Hall Effect file
92 May. 17 (Thu.), 01:30 PM  E6-2. 1st fl. #1323  Prof. Yong-Baek Kim University of Toronto  Quantum Spin Liquid in Kitaev Materials file
91 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
90 Oct. 12 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Daniel Kyungdeock Park  Quantum Advantage in Learning Parity with Noise file
89 May. 12 (Fri.), 01:30 PM  E6-2. 1st fl. #1323  Dr. Young Kuk Kim  Topological Dirac insulator
88 Nov. 9 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. Pilkyung Moon  Moiré superlattices – from twisted bilayer graphene to quasicrystal file
87 Sep. 22 (Fri.), 01:00 PM  E6-2. 1st fl. #1323  Dr. EunSeong Kim / Department of Physics, KAIST  Superconductor-metal-insulator transition in thin Tantalum films file
86 Sep. 22 (Fri.), 02:30 PM  E6-2. 1st fl. #1323  Dr. GilHo Lee / Department of Physics, POSTECH  Quantum Electronic Transport in Graphene Hybrid Nanostructures file