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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
66 June 4 (Tue.), 5:00 PM  #1323, E6-2  Prof. Minsu Kim  Stochastic nature of bacterial eradication using antibiotics file
65 May 31 (Fri.), 11:00 AM  #1323, E6-2  Prof. Guido Burkard  Cavity QED with Spin Qubits file
64 May 24 (Fri.), 16:00 PM  #1323, E6-2  Prof. Soonjae Moon  Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates file
63 May 30 (Thu.), 16:00 PM  #1323, E6-2  Prof. Chang-Hee Cho  Tuning the excitonic properties of semiconductors with light-matter interactions file
62 November 14 (Thu.), 16:00 PM  #1323, E6-2  Prof. Ji-Hun Kang  Semi-classical model of polariton propagation file
61 November 28 (Thu.), 16:00 PM  #1323, E6-2  Prof. Kyung Taec Kim  Generation of coherent EUV emissions using ultrashort laser pulses file
60 December 3 (Tue.), 4:00 PM  #1323, E6-2  Dr. Jong Mok Ok  Toward Quantum Materials with Correlated Oxides file
59 December 5 (Thu.), 16:00 PM  #1323, E6-2  Prof. Soon-Hong Kwon  Subwavelenth Photonic Devices: From Single Photon Sources to Solar Cell file
58 December 13 (Fri.), 1:30-4:30 PM  #1323, E6-2    Biophysics Mini-symposium at KAIST newfile
57 June 17 (Mon.), 10:30 AM  #1323, E6-2  Dr. See-Hun Yang  Chiral Spintronics file
56 June 28 (Fri.), 13:30 PM  #1323, E6-2  Dr. Yusuke Kozuka  Magnetic domains and domain wall conduction in pyrochlore iridate thin films and heterostructures file
55 July 30 (Tue), 4:00 PM  #1323, E6-2  Dr. Mingu Kang  Dirac fermions and flat bands in correlated kagome metals file
54 2019. 8. 22 4PM & 8. 23 3PM  #1323, E6-2  Prof. Andrew N Cleland  Physics and Applications in Nanoelectronics and Nonomechanics file
53 September 18(Wed.), 16:00PM  #1323, E6-2  Prof.David Schuster  Exploring Synthetic Quantum Matter in Superconducting Circuits file
52 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
51 October 15 (Tue.), 16:00 PM  #1323, E6-2  Prof. Pilkyung Moon  Moiré superlattices and graphene quasicrystal file
50 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
49 Oct. 25 (Fri), 15:00 ~  #1323, E6-2  Daesu Lee,Junwoo Son,MyungJoon Han ,Siheon Ryee,Eun-Gook Moon  Physics Seminar file
48 October 29 (Tue.), 14:30 PM  #1323, E6-2  Prof. Jörg Wrachtrup  Quantum sensing file
47 November 5 (Tue.), 4:00 PM  #1323, E6-2  Dr. Shik Shin  Study on nanomaterials by the development of ultrahigh resolution laser-photoelectron microscopy (PEEM) file