visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2016-06-01 16:00 
일시 Jun 1 (Wed) 4 PM 
장소 #1323(E6-2 1st fl.) 
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 날짜 장소 제목
361 2024-04-11 16:00  E6-2, Rm#1323  Theoretical Studies of the Electric Field Induced Thermal Hall Effect in the Quantum Dimer Magnets XCuCl3 (X = Tl, K)
360 2016-04-06 15:30  E6-2, RM #1323  Superconducting Quantum Interference Devices for Precision Detection
359 2017-12-15 09:20  E6-2, Lecture Room #1323  Workshop on Magnetism in Unconventional Superconductors 개최 file
358 2015-10-16 15:00  E6-2, 5th fl. #5318  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
357 2015-10-15 10:00  E6-2, 5th fl. #5318  Development of Large-Bore, High Field Magnets at the NHMFL
356 2018-06-14 10:00  E6-2, 2nd fl. #2502  Phonons and polariton-like particles in trapped ions for quantum computation and quantum simulation file
355 2019-07-03 15:00  E6-2, 2501  Many-body quantum electrodynamis (QED) with atoms and photons: A new platform for quantum optics" file
354 2016-03-11 13:30  E6-2, 1501 외  Physics Seminar Serises : 2016 Spring file
353 2015-07-16 16:00  E6-2, 1501  KAIST Physics Distinguished Lecture
352 2015-07-16 16:00  E6-2, 1318  Next-generation ultrafast laser technology for nonlinear optics and strong-field physics
351 2020-02-12 13:00  E6-2, #5318  From inflation to new weak-scale file
350 2015-11-06 16:30  E6-2, #5318  Topological Dirac line nodes in centrosymmetric semimetals
349 2015-10-23 15:00  E6-2, #5318  Development of a Rogowski Coil as a new beam position monitor
348 2023-11-22 10:00  E6-2, #5301 & zoom  [High Energy Theory Seminar] Exact Quantum Algorithms to Recognize Quantum Phases of Matter
347 2023-06-01 16:00  E6-2, #5301  Hall viscosity and topological phenomena
346 2023-09-13 16:00  E6-2, #2502  [High Energy Theory Seminar] Cosmic Birefringence from Dark Photon
345 2023-05-31 16:00  E6-2, #2502  [High-Energy Theory Seminar] Resurgence and complex Chern-Simons theory
344 2023-04-05 16:00  E6-2, #2502  [High Energy Theory Seminar]Anomalies of Discrete 1-Form Symmetries in QCD-like Theories
343 2024-05-14 16:00  E6-2, #2502  [High Energy Theory Seminar] Minimal Production of Prompt Gravitational Waves during Reheating.
342 2023-05-03 16:00  E6-2, #2502  Probing microscopic origins of axions by the chiral magnetic effect