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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
109 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
108 Sep10(Tue), 15:00  #2502, E6-2  Jun Ho Son  (2+1) D Duality Web from 3D Euclidean Lattice file
107 June 27 (Thu), 2:00 PM  #2502, E6-2  Hyun-Yong Lee  Gapless Kitaev Spin Liquid to Loop and String Gases file
106 April 6 (Fri.), 10:00 AM  #2502, E6  박채연 박사  Entanglement and thermalization in many-body systems: recent progress file
105 December 13 (Fri.), 1:00 PM  #2501, E6-2  Dr. Chang-Jong Kang  Computational Material Designs: Current Status and Future Directions file
104 Apr. 28 (Thu.) 3PM  #2501(E6-2. 2nd fl.)  Dr. Chang Hee Sohn, SEOUL NATIONAL UNIVERSITY  Lattice/Spin/Charge Coupling in 5d Pyrochlore Cd2Os2O7
103 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
102 October 4 (Thu.), 16:00 PM  #1323, E6-2  Prof. Soo Jin Kim  Engineering light absorption in an ultrathin semiconductor metafilm file
101 October 19 (Fri.), 10:00 AM  #1323, E6-2  Dr. Jongsoo Yoo  Energy conversion processes during magnetic reconnection in a laboratory plasma file
100 October 11 (Thu.), 16:00 PM  #1323, E6-2  Prof. Joung-Real Ahn  Dirac electrons in a graphene quasicrystal file
99 October 15 (Mon.), 16:00 PM  #1323, E6-2  Dr. Yongjoo Baek  Universal properties of macroscopic current-carrying systems file
98 October 15 (Tue.), 16:00 PM  #1323, E6-2  Prof. Pilkyung Moon  Moiré superlattices and graphene quasicrystal file
97 May 311 (Thu.), 04:00 PM  #1323, E6-2  Prof. Teun-Teun Kim  Dynamic control of optical properties with gated-graphene metamaterials file
96 May 9 (Wed.), 04:00 PM  #1323, E6-2  Prof. Jong-Soo Rhyee  Recent advances in thermoelectric bulk composites file
95 November 1 (Thu.), 16:00 PM  #1323, E6-2  Dr. KyeoReh Lee  Direct holography from a single snapshot file
94 October 29 (Tue.), 14:30 PM  #1323, E6-2  Prof. Jörg Wrachtrup  Quantum sensing file
93 September 26 (Thu.), 16:00 PM  #1323, E6-2  Han Seb Moon  Entanglement Swapping with Autonomous Polarization-Entangled Photon-Pairs from Warm Atomic Ensemble file
92 October 16 (Tue.), 10:00 AM  #1323, E6-2  Dr. Won-Ki Cho  Capturing protein cluster dynamics and gene expression output in live cells file
91 October 25 (Thu.), 4:00 PM  #1323, E6-2  Dr. Gang Li  Abelian and non-Abelian dark photons file