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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
39 October 15 (Mon.), 16:00 PM  #1323, E6-2  Dr. Yongjoo Baek  Universal properties of macroscopic current-carrying systems file
38 October 15 (Tue.), 16:00 PM  #1323, E6-2  Prof. Pilkyung Moon  Moiré superlattices and graphene quasicrystal file
37 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
36 October 16 (Wed), 4:00pm  #1323 (E6-2, 1st fl.)  Dr. Jaewon Song  Emergent black holes and monopoles from quantum fields file
35 October 17 (Thu.), 16:00 PM  #1323, E6-2  Prof. Namkyoo Park  Top down manipulation of Waves : From Metamaterials, Correlated Disorder, Quantum Analogy, to Digital Processing file
34 October 18 (Thu.), 10:00 AM  #1323, E6-2  Dr. Duyoung Min  Understanding membrane protein folding using single-molecule force techniques file
33 October 18 (Thu.), 16:00 PM  #1323, E6-2  Prof. Jongseok Lee  Applications of nonlinear optics for condensed matter researches file
32 October 19 (Fri.), 10:00 AM  #1323, E6-2  Dr. Jongsoo Yoo  Energy conversion processes during magnetic reconnection in a laboratory plasma file
31 October 24 (Wed.), 10:30 AM  E6-1, Lecture Room 1501(1F)  Prof. Kerry J. Vahala  Photonic integration of next-generation clocks and Hertz-absolute-accuarcy optical frequenncy synthesizers file
30 October 25 (Thu.), 4:00 PM  #1323, E6-2  Dr. Gang Li  Abelian and non-Abelian dark photons file
29 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
28 October 29 (Tue.), 10:00am  #1323 (E6-2, 1st fl.)  Prof. Se Kwon Kim  Unconventional Spin Transport in Quantum Materials file
27 October 29 (Tue.), 14:30 PM  #1323, E6-2  Prof. Jörg Wrachtrup  Quantum sensing file
26 October 29 (Tue.), 4:00pm  #1323 (E6-2, 1st fl.)  Dr. Seung-Joo Lee  Particles and Gravity via String Geometry file
25 October 31 (Thu.), 10:00am  #1323 (E6-2, 1st fl.)  Dr. Seung-Sup Lee  Kondo meets Hubbard: Impurity physics for correlated lattices file
24 October 4 (Thu.), 16:00 PM  #1323, E6-2  Prof. Soo Jin Kim  Engineering light absorption in an ultrathin semiconductor metafilm file
23 Sep. 02(Fri) 2:30 PM  E6-2(1st fl.), #1323  Dr. Yong-Hyun Kim,Graduate School of Nanoscience and Technology, KAIST  Nanoscale Thermal Physics: Seebeck Effect and Nanoscale Friction
22 Sep. 02(Fri) 4:00 PM  E6-2(1st fl) #1323  Dr. Yong-Joo Doh, Department of Physics and Photon Science, GIST  Quantum Electrical Transport in Topological Insulator Nanowires
21 Sep. 10 (Tue.), 03:00 PM  E6-2. 1st fl. #1323  Dr. Mikhail Kiselev  Two-Stage Kondo Effect file
20 Sep. 12 (Tue.), 4 PM  #1323 (E6-2. 1st fl.)  Prof. Yi. Zhou (The Zhejiang Univ.)  Exact Solution for the Interacting Kitaev Chain at Symmetric Point file