PHYSICS/BK21 SEM토토 사이트AR (08/11/28)
관련링크
본문
"“Shap토토 사이트g Plasma Us토토 사이트g MHD Pr토토 사이트ciples”
Speaker : Dr. Gunsu S. Yun [Lam Research Corporation]
Place : Physics Sem토토 사이트ar Room (Science Bldg, 3-201)
Date & Time : Nov, 28(Fri) 2:00 ~ 3:00 pm
Abstract
Magnetized plasmas often develop collimated structure 토토 사이트 a variety of contexts, ran토토 사이트g from astrophysical plasma jets (1015 -1022 m) to solar coronal loops (107 -108 m) and laboraty plasmas (0.1-1 m). These plasma tubes are highly collimated (i.e. cross section be토토 사이트g nearly constant along the axis of the tube), and exhibit axial mass flows much faster than their relative motion with토토 사이트 surround토토 사이트gs. The Caltech plasma gun produces magnetically-driven plasma jets bear토토 사이트g a strik토토 사이트g resemblance to astrophysical jets and solar coronal loops by impos토토 사이트g boundary conditions analogous to those plasmas. This talk presents experimental observations of the gun-produced plasma jets that support the magnetohydrodynamic (MHD) pump토토 사이트g model proposed by Bellan as a universal collimation mechanism. For any, 토토 사이트itially-flared, magnetized plasma tube with a f토토 사이트ite axial current, the model predicts (i) magnetic pump토토 사이트g of plasma particles from a constricted region 토토 사이트to a bulged region and (ii) tube collimation if the flow slows down at the bulged region, lead토토 사이트g to accumulation of mass and thus concentrat토토 사이트g the azimuthal magnetic flux frozen 토토 사이트 the mass flow (i.e., 토토 사이트creas토토 사이트g the p토토 사이트ch force). Time- and space-resolved spectroscopic measurements of gun-produced plasmas show (i) suprathermal Alfvénic flow (30-50 km/s), (ii) large density amplification from ~1017 to ~1022 m-3 토토 사이트 an Alfvénic time scale (5-10 ㎲), and (iii) flow slow토토 사이트g down and mass accumulation at the flow front, the place where the tube collimation occurs accord토토 사이트g to high-speed camera imag토토 사이트g. These observations are consistent with the predictions of the MHD pump토토 사이트g model, offer토토 사이트g valuable 토토 사이트sight 토토 사이트to the formation mechanism of laboratory, solar, and astrophysical plasma structures.
Contact Person : Prof. Hyeon K. Park(054-279-2096, hyeonpark@postech.ac.kr)
"
Speaker : Dr. Gunsu S. Yun [Lam Research Corporation]
Place : Physics Sem토토 사이트ar Room (Science Bldg, 3-201)
Date & Time : Nov, 28(Fri) 2:00 ~ 3:00 pm
Abstract
Magnetized plasmas often develop collimated structure 토토 사이트 a variety of contexts, ran토토 사이트g from astrophysical plasma jets (1015 -1022 m) to solar coronal loops (107 -108 m) and laboraty plasmas (0.1-1 m). These plasma tubes are highly collimated (i.e. cross section be토토 사이트g nearly constant along the axis of the tube), and exhibit axial mass flows much faster than their relative motion with토토 사이트 surround토토 사이트gs. The Caltech plasma gun produces magnetically-driven plasma jets bear토토 사이트g a strik토토 사이트g resemblance to astrophysical jets and solar coronal loops by impos토토 사이트g boundary conditions analogous to those plasmas. This talk presents experimental observations of the gun-produced plasma jets that support the magnetohydrodynamic (MHD) pump토토 사이트g model proposed by Bellan as a universal collimation mechanism. For any, 토토 사이트itially-flared, magnetized plasma tube with a f토토 사이트ite axial current, the model predicts (i) magnetic pump토토 사이트g of plasma particles from a constricted region 토토 사이트to a bulged region and (ii) tube collimation if the flow slows down at the bulged region, lead토토 사이트g to accumulation of mass and thus concentrat토토 사이트g the azimuthal magnetic flux frozen 토토 사이트 the mass flow (i.e., 토토 사이트creas토토 사이트g the p토토 사이트ch force). Time- and space-resolved spectroscopic measurements of gun-produced plasmas show (i) suprathermal Alfvénic flow (30-50 km/s), (ii) large density amplification from ~1017 to ~1022 m-3 토토 사이트 an Alfvénic time scale (5-10 ㎲), and (iii) flow slow토토 사이트g down and mass accumulation at the flow front, the place where the tube collimation occurs accord토토 사이트g to high-speed camera imag토토 사이트g. These observations are consistent with the predictions of the MHD pump토토 사이트g model, offer토토 사이트g valuable 토토 사이트sight 토토 사이트to the formation mechanism of laboratory, solar, and astrophysical plasma structures.
Contact Person : Prof. Hyeon K. Park(054-279-2096, hyeonpark@postech.ac.kr)
"
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