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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
146 2009/09/07-11/30  E6, 1501  이주영박사(KIAS) 외  Physics Colloquium : 2009 Fall file
145 2009/10/21, 4PM  E6, 1501  최석봉교수(서울대)  Interdimensional Universality of Dynamic Interfaces
144 2010/02/08-05/03  E6, 1501  최인수교수(서울대) 외  Physics Ciolloquium : 2010 Spring file
143 2010/09/06-12/06  E6, 1501  조호진기자(조선일보) 외  Physics Colloquium : 2010 Fall file
142 2010/02/14-05/09  E6, 1501  황철주(주성엔지니어링 사장) 외  Physics Colloquium - 2011 Spring file
141 2011/05/16, 4PM  E6, 1501  서민교교수(KAIST)  Photonics with surface plasmon polaritons
140 2011/09/03-12/06  E6, 1501  김용균교수(한양대) 외  Physics Colloquium : 2011 Fall file
139 2012/02/13-05/14  E6, 1501  Kenji Ohmori (Photo-Molecular Science, IMS)  Physics Colloquium : 2012 Spring
138 2012/04/02, 4PM  E6, 1501  Yong Hee Jeong  A new route to ferroelectricity in magnetic spinels: a case of Co2MnO4
137 2013/03/11-06/10  E6, 1501  강명수교수(KAIST) 외  Physics Colloquium : 2013 Spring
136 2013/09/09-12/09  E6, 1501  박혁규교수(부산대) 외  Physics Colloquium : 2013 Fall
135 2014/03/10-06/09  E6, 1501  신용일교수(서울대)  Physics Colloquium : 2014 Spring file
134 2015/09/15-12/08  E6, 1501  박제근 교수(서울대 물리학과) 외12명  Physics Colloquium : 2014 Fall file
133 2015/03/09-06/08  E6, 1501  최현용교수(연세대) 외12명  Physics Colloquium : 2015 Spring file
132 2015/09/07-12/01  E6, 1501  문은국 교수(KAIST) 외  Physics Colloquium : 2015 Fall file
131 2016/03/07-06/13  E6, 1501  Prof. David Helfman(KAIST) 외  Physics Colloquium : 2016 Spring file
130 2015/10/23-12/4 10:30 AM  E6, #1501  Prof. YongKeun Park & Prof. Tae-Young Yoon  How to write a good scientific paper[Open lecture series]
129 July 8(Mon), 14:00  E6, #1322  T. L. M. Guedes (Univ. of Konstanz)  Ultrabroadband squeezed pulses and their relation to relativity file
128 Nov. 22th (Thur), 15:00  E6 Room(#1323)  Prof. Suprijadi Haryono  Experimental and Computational Study on Physical Properties based on Granular System file
127 May. 8th (Wed), 16:00  E6 Room(#1323)  Jieun Lee  Imaging valley dependent electron transport in 2D semiconductors file