Effect of sheath potential on electromagnetic radiation emitted from the rear surface of a metallic foil target  

作　　者：郑坚 李志超 张辉 俞昌旋 薮内俊毅 田中和夫 

机构地区：[1]Key Laboratory of Basic Plasma Physics, Chinese Academy of Sciences, Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China [2]Institute of Laser Engineering, Osaka University, 2-6 Yarnada-oka, Suita, Osaka 565-0871, Japan

出　　处：《Chinese Physics B》2007年第10期3009-3015,共7页中国物理B（英文版）

摘　　要：In ultra-intense laser-matter interactions, intense electric fields formed at the rear surface of a foil target may have strong influences on the motion of energetic electrons, and thereby affect the electromagnetic emissions from the rear surface, usually ascribed to transition radiation. Due to the electric fields, transition radiation occurs twice and bremsstrahlung radiation also happens because the electrons will cross the rear surface twice and have large accelerations. In the optic region, transition radiation is dominant. The radiation spectrum depends on the electric field only when the electrons are monochromatic, and becomes independent of the electric field when the electrons have a broadband momentum distribution. Therefore, in an actual experiment, the electric field at the rear surface of a foil could not be studied just with the measurement of optic emissions. In the terahertz region, both bremsstrahlung and transition radiations should be taken into account, and the radiation power could be enhanced in comparison with that without the inclusion of bremsstrahlung radiation. The frequency at which the maximum terahertz radiation appears depends on the electric field.In ultra-intense laser-matter interactions, intense electric fields formed at the rear surface of a foil target may have strong influences on the motion of energetic electrons, and thereby affect the electromagnetic emissions from the rear surface, usually ascribed to transition radiation. Due to the electric fields, transition radiation occurs twice and bremsstrahlung radiation also happens because the electrons will cross the rear surface twice and have large accelerations. In the optic region, transition radiation is dominant. The radiation spectrum depends on the electric field only when the electrons are monochromatic, and becomes independent of the electric field when the electrons have a broadband momentum distribution. Therefore, in an actual experiment, the electric field at the rear surface of a foil could not be studied just with the measurement of optic emissions. In the terahertz region, both bremsstrahlung and transition radiations should be taken into account, and the radiation power could be enhanced in comparison with that without the inclusion of bremsstrahlung radiation. The frequency at which the maximum terahertz radiation appears depends on the electric field.

关 键 词：sheath potential transition radiation bremsstrahlung radiation energetic electrons 

分 类 号：O562[理学—原子与分子物理]