visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2016-06-01 16:00 
연사  
장소 #1323(E6-2 1st fl.) 

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 연사 제목
공지 2025-02-24 16:00    2025년 봄학기 콜로키움 안내
공지 2025-02-27 16:00    2025년 봄 물리학과 특별세미나 (광학/응집물리 분야)
234 2022-05-30 16:00    Light manipulation using 2D layered semiconductors
233 2022-06-03 09:30    (Quantum-&Nano-Photonics Webinar) Seeing glass in a new light: reimagine chalcogenide photonics file
232 2022-06-03 11:00    (응집물리 세미나) Theoretical Investigation of Exotic Quantum States in Low-dimensional Materials
231 2022-06-10 11:00    Record-quality two-dimensional electron systems file
230 2022-06-10 14:30    Combinatorial strategy for condensed matter physics: study on rare earth hexaborides thin films file
229 2022-06-10 16:00    Fe5GeTe2의 나선형 자성특성과 자기저항의 전류밀도 의존성 연구 file
228 2022-06-23 11:00    JILA’s search for the electron’s Electric Dipole Moment (eEDM) to probe physics beyond the standard model file
227 2022-07-14 13:30    Electronic structure and anomalous transport properties of topological materials by first principle calculation
226 2022-07-14 14:15    Hund and electronic correlations in ruthenium-based systems
225 2022-07-14 15:00    Pure two-dimensional quantum electron liquid and its phase transition
224 2022-07-21 16:00    Quintessential axions file
223 2022-08-01 10:00    [Update 세미나 영상] James Webb Space Telescope & OTE Commissioning
222 2022-08-08 14:00    Classical Shadow Tomography for Analog Quantum Simulators
221 2022-08-09 14:00    Quantum biology in fluorescent protein: a new model system to study quantum effects in biology file
220 2022-08-12 10:00    Twisted Bilayer Magnets file
219 2022-08-12 10:00    Twisted Bilayer Magnets file
218 2022-08-17 11:00    Robust Hamiltonian Engineering of Large Quantum Systems (큰 양자시스템의 견고한 해밀토니안 엔지니어링)
217 2022-08-18 10:00    Disorder-driven phase transition in the second-order non-Hermitian skin effect
216 2022-09-15 13:00    AdS black holes: a review
215 2022-09-21 10:30    [Update 세미나 영상] Distinguished Lecture 'The Magic of Moiré Quantum Matter' Prof. Pablo Jarillo-Herrero(Department of Physics, MIT) file