PHYSICS/BK21 SEMINAR (08/11/28)
관련링크
본문
"“Shaping Plasma Using MHD Principles”
Speaker : Dr. Gunsu S. Yun [Lam Research Corporation]
Place : Physics Seminar Room (Science Bldg, 3-201)
Date & Time : Nov, 28(Fri) 2:00 ~ 3:00 pm
Abstract
Magnetized plasmas often develop collimated structure in a variety of contexts, raning 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 being nearly constant along the axis of the tube), and exhibit axial mass flows much faster than their relative motion within surroundings. The Caltech plasma gun produces magnetically-driven plasma jets bearing a striking resemblance to astrophysical jets and solar coronal loops by imposing boundary conditions analogous to those plasmas. This talk presents experimental observations of the gun-produced plasma jets that support the magnetohydrodynamic (MHD) pumping model proposed by Bellan as a universal collimation mechanism. For any, initially-flared, magnetized plasma tube with a finite axial current, the model predicts (i) magnetic pumping of plasma particles from a constricted region into a bulged region and (ii) tube collimation if the flow slows down at the bulged region, leading to accumulation of mass and thus concentrating the azimuthal magnetic flux frozen in the mass flow (i.e., increasing the pinch 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 in an Alfvénic time scale (5-10 ㎲), and (iii) flow slowing down and mass accumulation at the flow front, the place where the tube collimation occurs according to high-speed camera imaging. These observations are consistent with the predictions of the MHD pumping model, offering valuable insight into 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 Seminar Room (Science Bldg, 3-201)
Date & Time : Nov, 28(Fri) 2:00 ~ 3:00 pm
Abstract
Magnetized plasmas often develop collimated structure in a variety of contexts, raning 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 being nearly constant along the axis of the tube), and exhibit axial mass flows much faster than their relative motion within surroundings. The Caltech plasma gun produces magnetically-driven plasma jets bearing a striking resemblance to astrophysical jets and solar coronal loops by imposing boundary conditions analogous to those plasmas. This talk presents experimental observations of the gun-produced plasma jets that support the magnetohydrodynamic (MHD) pumping model proposed by Bellan as a universal collimation mechanism. For any, initially-flared, magnetized plasma tube with a finite axial current, the model predicts (i) magnetic pumping of plasma particles from a constricted region into a bulged region and (ii) tube collimation if the flow slows down at the bulged region, leading to accumulation of mass and thus concentrating the azimuthal magnetic flux frozen in the mass flow (i.e., increasing the pinch 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 in an Alfvénic time scale (5-10 ㎲), and (iii) flow slowing down and mass accumulation at the flow front, the place where the tube collimation occurs according to high-speed camera imaging. These observations are consistent with the predictions of the MHD pumping model, offering valuable insight into the formation mechanism of laboratory, solar, and astrophysical plasma structures.
Contact Person : Prof. Hyeon K. Park(054-279-2096, hyeonpark@postech.ac.kr)
"
-2.gif)
Login
