visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
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
54 2016/03/07-06/13  E6, 1501  Prof. David Helfman(KAIST) 외  Physics Colloquium : 2016 Spring file
53 2015/12/17, 11:00AM  E4(KI Building), Matrix Hall (2nd fl.)  Dr. Jung-Hoon Park (Purdue University)  Wavefront engineering for in-vivo Deep brain imaging
52 2015/12/11, 3:45PM  E6-2, #1323  Dr. Ji Hun Sim (POSTECH)  Dynamical mean field theory studies on heavy fermion system
51 2015/12/11, 1:30PM  E6-2, #1323  Dr. KwangYong Choi  (Chung-Ang University)  Quantum spin liquid in the 1/3 depleted triangular lattice Ba3(Ru1-xIrx)Ti2O9
50 2015/12/09, 2PM  E6-2, #1323  Arjun G. Yodh (University of Pennsylvania)  SWELLABLE COLLOIDAL PARTICLES ARE SWELL
49 2015/12/09, 11AM  E4(KI Building), Connect room (2nd fl.)  Arjun G. Yodh (University of Pennsylvania)  Functional Imaging & Monitoring of Brain & Breast with Diffuse Light
48 2015/12/03, 4PM  E6-2, #1323  Dr. Sang-Yun Lee (3rd institute of Physics, University of Stuttgart, Germany)  Hybrid solid state spin qubits in wide bandgap semiconductors
47 2015/12/02, 4PM  E6-2, #1323  Dr. Dae-Jeong Kim (Dept. of Physics and Astronomy, University of California, Irvine)  Samarium Hexaboride: Is it a Topological insulator?
46 2015/12/01, 4PM  E6-2, #1323  Dr. Yeong Kwan Kim(Lawrence Berkeley National Laboratory, USA)  Introducing extra dimensions to spectroscopic studies of advanced quantum materials
45 2015/11/28, 10AM  E6-2, #1323  Dr. Suyong Jung (Korea Research Institute of Standards and Science)  Electron Tunneling Spectroscopy of Single and Bilayer Graphene with Hexagonal Boron Nitride as Tunneling Barrier
44 2015/11/24, 4PM  E6-2, #1323  Dr. Kab-Jin Kim (Institute for Chemical Research, Kyoto University, Japan)  Topology-based understanding of spin dynamics in inhomogeneously magnetized systems
43 2015/11/23, 1:30PM  E6-2, #1323  Dr. Michael Park (Stanford University)  What's Beyond the Standard Model? Lessons from Run I and what might come in Run II
42 2015/11/19, 4PM  E6-2, #1323  Dr. Daesu Lee (University of Wisconsin-Madison)  Emergent Collective Phenomena and Functions at Reduced Dimensions
41 2015/11/10, 4PM  E6-2, #1323  Dr. Woosuk Bang (Physics division, Los Alamos National Laboratory)  Rapid heating of matter using high power lasers
40 2015/11/06, 4:30 PM  E6-2, #5318  Dr. Youngkuk Kim (University of Pennsylvania)  Topological Dirac line nodes in centrosymmetric semimetals
39 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]
38 2015/10/23, 3PM  E6-2, #5318  Dr. Helmut Soltner (Forschungszentrum Juelich)  Development of a Rogowski Coil as a new beam position monitor
37 2015/10/16, 4PM  E6-2. 2nd fl. #2501  Prof. Yung-Fu Chen(Solid-state Laser Physics Laboratory,National Central University)  Fluctuations of entropy production in partially masked electric circuits
36 2015/10/16, 3PM  E6-2, 5th fl. #5318  Dr. Pierre Pugnat , (CNRS-LNCMI)  High Magnetic Fields to Probe the sub-eV range of Particle/Astroparticle Physics - From the OSQAR experiments at CERN up to new perspectives at LNCMI-Grenoble
35 2015/10/15, 10AM  E6-2, 5th fl. #5318  Dr. Mark D. Bird (Florida State University)  Development of Large-Bore, High Field Magnets at the NHMFL