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
247 2023-01-12 14:40  E6-2 #1323  JILA 1D Wannier-Stark optical lattice clock file
246 2018-07-26 14:00  Room 5318, KAIST Natural Sciences Lecture Hall(E6).  Inflation in String Theory and Backreaction file
245 2018-07-26 14:00  Room 5318, KAIST Natural Sciences Lecture Hall(E6).  Inflation in String Theory and Backreaction file
244 2023-08-29 16:00  E6-2, #2502  [High Energy Theory Seminar] Towards string loop corrections in Calabi-Yau orientifold compactifications.
243 2020-08-17 20:00  Zoom webinar  Using magnetic tunnel junctions to compute like the brain file
242 2020-08-25 20:00  Zoom webinar  KAIST Global Forum for Spin and Beyond (Second Forum) file
241 2023-06-14 16:00  E6-2, #2502  [High-Energy Theory Seminar]Vertex algebras and extended operators in 4d N=2 SCFTs
240 2023-06-22 16:00  E6-2,1323  [High Energy Physics Seminar] The Branes Behind Generalized Symmetry Operators
239 2019-01-23 16:00  Rm. C303, Creation Hall (3F), Munji Campus  Ultrasensitive Microwave Bolometer: Opportunity for Axion Detectors file
238 2022-04-13 10:30  E6 #1323/zoom  Harnessing topology and correlations from singularities in 3d-kagome metals
237 2023-08-23 16:00  E6-2, #1322  [High Energy Theory Seminar] A spacetime tensor network for AdS3/CFT2
236 2023-01-09 16:00  E6-2 #1323  Non-Hermitian Hopf-bundle Matter. Moon Jip Park (IBS-PCS)
235 2020-12-11 14:30  online  Antisymmetric interlayer exchange coupling in magnetic multilayers
234 2024-01-24 15:00  E6-2 #1323  Determination of single molecule loading rate during mechanotransduction file
233 2020-11-26 16:00  Online(Zoom)  2020 가을학기 광학분야 특별세미나(Light Engineering Beyond the Diffraction Limit)
232 2016-10-17 11:00  #1323,(E6-2, 1st fl.)  IMS and examples of the studies on optoelectronic materials
231 2019-08-19 10:00  Rm. 1322, E6-2  Tutorials on Multimode Quantum Optics in the Continuous Variable Regime file
230 2022-09-21 10:30  E6-1 #1501  [Update 세미나 영상] Distinguished Lecture 'The Magic of Moiré Quantum Matter' Prof. Pablo Jarillo-Herrero(Department of Physics, MIT) file
229 2022-08-08 14:00  E6-2 #2502  Classical Shadow Tomography for Analog Quantum Simulators
228 2020-12-09 10:00  Zoom  Searching for the QCD axion with the ARIADNE experiment file