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
356 2019-04-23 16:00  #1323, E6-2  From Mott physics to high-temperature superconductivity file
355 2022-07-21 16:00  CAPP Seminar Room C303, Creation Hall, KAIST Munji Campus  Quintessential axions file
354 2019-11-14 16:00  #1323, E6-2  Semi-classical model of polariton propagation file
353 2017-12-15 09:20  E6-2, Lecture Room #1323  Workshop on Magnetism in Unconventional Superconductors 개최 file
352 2024-05-01 16:00  E6-2 #2502  [High Energy Theory Seminar] Across the Mass Spectrum: Utilizing Small-Scale Structures to Probe Dark Matters
351 2019-11-07 16:00  #1323, E6-2  Integrated quantum photonics with solid-state quantum emitters file
350 2018-05-29 16:00  #1323, E6-2  Investigation on metal nanostructure/semiconductor junction and its applications file
349 2020-10-23 14:00  E6-2 #1323  Plasmon spectroscopy of low-dimensional superconductors in fluctuating regime file
348 2024-05-16 16:00  E6-2, #1323  [High Energy Theory Seminar] Conformal Collider Physics
347 2018-07-13 14:00  Room 5318, KAIST Natural Sciences Lecture Hall(E6).  Loop Induced Single Top Partner Production and Decay at the LHC
346 2018-12-11 16:00  E6-2. 1st fl. #1323  Natural compact representation of Matsubara Green’s functions: applications to analytic continuation and quantum many-body simulations file
345 2017-08-31 14:00  #5318(E6-2. 5th fl.)  “Berry phase and nonlinear response: photocurrent in noncentrosymmetric insulators and Weyl semimetals” file
344 2023-06-08 16:00  E6-2, #1323  Thermal decoupling in high-Tc cuprate superconductors
343 2019-05-31 11:00  #1323, E6-2  Cavity QED with Spin Qubits file
342 2022-05-27 11:00  Online seminar  Current Status and Future Plans of ADMX file
341 2015-07-23 13:30  E4, B401  Enhanced ZnO based UV photonics and related applications file
340 2020-10-15 16:00  CAPP Seminar Room #C303, Creation Hall (3F), KAIST Munji Campus  Graphene-based Josephson junction microwave bolometer file
339 2022-06-03 11:00  E6-2 #1323  (응집물리 세미나) Theoretical Investigation of Exotic Quantum States in Low-dimensional Materials
338 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
337 2022-09-21 16:00  College of Natural Science E6-2, Rm. 1323  Materials and Device Nanofabrication of Optical Metasurfaces file