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
322 2019-05-31 11:00  #1323, E6-2  Cavity QED with Spin Qubits file
321 2022-05-27 11:00  Online seminar  Current Status and Future Plans of ADMX file
320 2015-07-23 13:30  E4, B401  Enhanced ZnO based UV photonics and related applications file
319 2020-10-15 16:00  CAPP Seminar Room #C303, Creation Hall (3F), KAIST Munji Campus  Graphene-based Josephson junction microwave bolometer file
318 2022-06-03 11:00  E6-2 #1323  (응집물리 세미나) Theoretical Investigation of Exotic Quantum States in Low-dimensional Materials
317 2023-03-27 15:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  A coherent mechanical oscillator pumped by a suspended quantum dot file
316 2022-09-21 16:00  College of Natural Science E6-2, Rm. 1323  Materials and Device Nanofabrication of Optical Metasurfaces file
315 2023-11-01 16:00  E6-2, #2502  [High Energy Theory Seminar] Modular functions and 3D N=4 rank-zero superconformal field theories
314 2019-02-21 16:00  #5313, E6-2  B-meson charged current anomalies - Theoretical status file
313 2023-03-30 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  Detecting axions with chiral magnetic effects file
312 2019-09-18 16:00  Seminar Room #1323  Fall 2019: Physics Seminar Serises file
311 2016-03-07 16:00  E6, 1501  Physics Colloquium : 2016 Spring file
310 2023-11-15 16:00  E6-6, #119  Quantum hydrodynamic theory for plasmonics: from molecule-coupling to nonlinear optics
309 2022-10-04 16:00  E6 #2501  Distinguishing 6d (1, 0) SCFTs
308 2015-03-04 12:00  1323호, E6-2  Bioimaging and Biosensing Using Near-Infrared Fluorescence file
307 2019-05-03 11:00  E6-2. 2st fl. #2502  Exotic Magnetism file
306 2014-12-22 14:00  E6, Rm1319  Dynamics of molecular motors: Power stroke vs Brownian ratchet file
305 2019-05-30 16:00  #1323, E6-2  Tuning the excitonic properties of semiconductors with light-matter interactions file
304 2023-10-11 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  [CAPP seminar] Particle Physics with Neutrinos file
303 2018-07-09 14:00  #1323, E6-2  The principles of collective learning file