Laser-filament-induced snow formation in a subsaturated zone in a cloud chamber: experimental and theoretical study.
1 kHz, 2 mJ, 45 fs, 800 nm laser pulses were fired into a laboratory diffusion cloud chamber through a subsaturated zone (relative humidity ∼73%, T ∼ 4.3 °C). After 60 min of laser irradiation, an oval-shaped snow pile was observed right below the filament center and weighed ∼12.0 mg. The air current velocity at the edge of the vortices was estimated to be ∼16.5 cm/s. Scattering scenes recorded from the side show that filament-induced turbulence were formed inside the cloud chamber with two vortices below the filament. Two-dimensional simulations of the air flow motion in two cross sections of the cloud chamber confirm that the turbulent vortices exist below the filament. Based upon this simulation, we deduce that the vortices indeed have a three-dimensional elliptical shape. Hence, we propose that inside vortices where the humidity was supersaturated or saturated the condensation nuclei, namely, HNO(3), N(2)(+), O(2)(+) and other aerosols and impurities, were activated and grew in size. Large-sized particles would eventually be spun out along the fast moving direction towards the cold plate and formed an oval-shaped snow pile at the end.
Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Laser (COPL), Laval University, Quebec City, QC G1V 0A6, Canada and State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Jingjing
J
Ju
State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Haiyi
H
Sun
Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Laser (COPL), Laval University, Quebec City, QC G1V 0A6, Canada.
Aravindan
A
Sridharan
Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Laser (COPL), Laval University, Quebec City, QC G1V 0A6, Canada and State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Tie-Jun
TJ
Wang
State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Cheng
C
Wang
State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Jiansheng
J
Liu
State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Ruxin
R
Li
State Key Lab of High Laser Field Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, No. 390, Qinghe Road, Jiading District, Shanghai 201800, China.
Zhizhan
Z
Xu
Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Laser (COPL), Laval University, Quebec City, QC G1V 0A6, Canada.
See Leang
SL
Chin