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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
92 June 27 (Wed.), 13:30 PM  #1323, E6-2  Dr. Jung Sik Park  Magnetic reversal of artificial spin ice file
91 May 9 (Wed.), 04:00 PM  #1323, E6-2  Prof. Jong-Soo Rhyee  Recent advances in thermoelectric bulk composites file
90 May 29 (Tue.), 04:00 PM  #1323, E6-2  Prof. Jae-Won Jang  Investigation on metal nanostructure/semiconductor junction and its applications file
89 May 311 (Thu.), 04:00 PM  #1323, E6-2  Prof. Teun-Teun Kim  Dynamic control of optical properties with gated-graphene metamaterials file
88 June 22 (Fri.), 04:00 PM  #1323, E6-2  Dr. Daniel Sando  Tuning functional properties of BiFeO3 films using strain and growth chemistry file
87 June 22 (Fri.), 04:00 PM  #1323, E6-2  Dr. Daniel Sando  Tuning functional properties of BiFeO3 films using strain and growth chemistry file
86 July 9 (Mon.), 14:00 PM  #1323, E6-2  Prof. Cesar A. Hidalgo, MediaLab, MIT  The principles of collective learning file
85 October 25 (Thu.), 4:00 PM  #1323, E6-2  Dr. Gang Li  Abelian and non-Abelian dark photons file
84 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
83 November 1 (Thu.), 16:00 PM  #1323, E6-2  Dr. KyeoReh Lee  Direct holography from a single snapshot file
82 November 8 (Thu.), 16:00 PM  #1323, E6-2  이종완 박사  Conformality lost file
81 November 21 (Wed.), 15:00 PM  #1323, E6-2  Prof. Seongshik Oh  Engineering topological quantum physics at the atomic scale file
80 November 29 (Thu.), 16:00 PM  #1323, E6-2  Dr. Kee suk Hong  양자 칸델라 실현을 위한 단일 광자 발생장치 개발 file
79 April 4 (Thu.), 16:00 PM  #1323, E6-2  Prof. Su-Hyun Gong  Chiral spin-photon interaction at nanoscale file
78 April 11 (Thu.), 16:00 PM  #1323, E6-2  Prof. Joo-Hyoung Lee, GIST  Massive screening for cathode active materials using deep neural network file
77 Apr.19 (Fri.), 11:00 AM  #1323, E6-2  Dr. Ji-Sang Park  First-principles studies of semiconductors for solar cell applications file
76 April 23 (Tue.), 4:00 PM  #1323, E6-2  Prof. Johan Chang  From Mott physics to high-temperature superconductivity file
75 April 26 (Fri.), 4:00 PM  #1323, E6-2  Dr. Soonwon Choi  Robust Quantum Metrology using Strongly Interacting Spin Ensembles and Quantum Convolutional Neural Network file
74 May 1 (Wed), 4:00 PM  #1323, E6-2  Dr. Sungkyun Choi  Raman and x-ray scattering study on correlated electron systems: two case examples file