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
공지 2022-11-25 11:00  E6-2 #1323  [Update 세미나영상](응집물리 세미나) DMFT+ NRG: From models to real materials, from local to nonlocal correlations
237 2019-06-27 14:00  #2502, E6-2  Gapless Kitaev Spin Liquid to Loop and String Gases file
236 2019-06-24 11:00  E6-2, #1323  Topological photonic anomalies file
235 2019-06-17 10:30  #1323, E6-2  Chiral Spintronics file
234 2019-06-12 15:00  Rm# 1323, E6-2  The relation between free and interacting fermionic SPT phases file
233 2019-06-04 17:00  #1323, E6-2  Stochastic nature of bacterial eradication using antibiotics file
232 2019-05-31 11:00  #1323, E6-2  Cavity QED with Spin Qubits file
231 2019-05-30 16:00  #1323, E6-2  Tuning the excitonic properties of semiconductors with light-matter interactions file
230 2019-05-24 16:00  #1323, E6-2  Infrared spectroscopy study on metal-insulator transitions in layered perovskite iridates file
229 2019-05-21 16:00  #5318, E6-2  Classification of flat bands according to the band-crossing singularity of Bloch wave functions file
228 2019-05-09 16:00  #1323, E6-2  Quantum Optical Sensing Using Single Photons And Single Photon Emission from Single Emitters file
227 2019-05-08 16:00  E6 Room(#1323)  Imaging valley dependent electron transport in 2D semiconductors file
226 2019-05-03 11:00  E6-2. 2st fl. #2502  Exotic Magnetism file
225 2019-05-02 16:00  #1323, E6-2  Anomalous optical properties of halide perovskites file
224 2019-05-01 16:00  #1323, E6-2  Raman and x-ray scattering study on correlated electron systems: two case examples file
223 2019-04-26 16:00  #1323, E6-2  Robust Quantum Metrology using Strongly Interacting Spin Ensembles and Quantum Convolutional Neural Network file
222 2019-04-23 16:00  #1323, E6-2  From Mott physics to high-temperature superconductivity file
221 2019-04-19 16:00  E6-2. 1st fl. #1323  Graphene and hBN heterostructures file
220 2019-04-19 14:30  E6-2. 1st fl. #1323  A family of finite-temperature electronic phase transitions in graphene multilayers file
219 2019-04-19 11:00  #1323, E6-2  First-principles studies of semiconductors for solar cell applications file
218 2019-04-11 16:00  #1323, E6-2  Massive screening for cathode active materials using deep neural network file