J. Phys. IV France 11 (2001) Pr2-211-Pr2-216
Studies on fast electrons in ultrashort pulse laser plasmasJ. Zhang1, L.Z. Zhao1, L.M. Chen1, P. Zhang1, 2, T. J. Liang1, L. Wang1 and Z. M. Sheng3
1 Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
2 Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China
3 Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565, Japan
Studies on the fast electrons escaped into vacuum are reported from solid targets illuminated by 150-fs laser pulses with p-polarised oblique incidence at a modest irradiance of [MATH]. The escaping electrons were found to form a jet in the normal direction to the target surface. The fast varying charge separation current can be measured by an LCR circuit, which converts the instantaneous charging current into a slow discharge process during the interaction. The total number of the escaping electrons is, for the first time, accurately determined to be 7x109 by direct measurement of the charge separation potential generated during the interaction. The average energy of the escaping electrons was also accurately measured to be around 60 keV. The energy conversion from laser to these escaping fast electrons was found to be as high as 1.3% at such a modest irradiance.
© EDP Sciences 2001