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
402 2023-07-20 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  [CAPP Seminar] Cosmoparticle Physics of Dark Universe file
401 2022-07-21 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  Quintessential axions file
400 2022-09-21 16:00  College of Natural Science E6-2, Rm. 1323  Materials and Device Nanofabrication of Optical Metasurfaces file
399 2015-03-13 14:00  Connect Room, KI Bldg.  The 15th Innovative Workshop on Soft/Bio Materials file
398 2015-12-09 11:00  E4(KI Building), Connect room (2nd fl.)  Functional Imaging & Monitoring of Brain & Breast with Diffuse Light
397 2015-12-17 11:00  E4(KI Building), Matrix Hall (2nd fl.)  Wavefront engineering for in-vivo Deep brain imaging
396 2015-07-23 13:30  E4, B401  Enhanced ZnO based UV photonics and related applications file
395 2023-05-17 14:00  E6 #1323  Optical Response in the multilayer thin films
394 2023-04-28 11:00  E6 #1323  Tkachenko wave: From the modern field theory viewpoint
393 2022-10-06 13:00  E6 #1323  Counting States with Global Symmetry
392 2022-04-13 10:30  E6 #1323/zoom  Harnessing topology and correlations from singularities in 3d-kagome metals
391 2022-01-11 15:00  E6 #1501  Ultrafast optical studies on CDW collective modes of the Weyl-CDW (TaSe4)2I file
390 2022-01-26 13:00  E6 #1501  An Introduction to Cohomology groups file
389 2022-07-14 14:15  E6 #1501 & Zoom  Hund and electronic correlations in ruthenium-based systems
388 2022-08-01 10:00  E6 #1501 & Zoom  [Update 세미나 영상] James Webb Space Telescope & OTE Commissioning
387 2022-07-14 13:30  E6 #1501 & Zoom  Electronic structure and anomalous transport properties of topological materials by first principle calculation
386 2022-07-14 15:00  E6 #1501 & Zoom  Pure two-dimensional quantum electron liquid and its phase transition
385 2022-10-24 16:00  E6 #1501(공동강의실)  Physics Colloquim(Fall 2022) file
384 2022-01-25 15:00  E6 #1501/online  Emulating twisted double bilayer graphene with a multiorbital optical lattice file
383 2022-03-31 10:00  E6 #1501/zoom  Weiss fields for Quantum Spin Dynamics file