Krainov V P
Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Moscow Region, Russia.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Aug;68(2 Pt 2):027401. doi: 10.1103/PhysRevE.68.027401. Epub 2003 Aug 7.
The yield of high-order harmonics has been derived for relativistic plasmas of multicharged atomic ions produced by an intense, linearly polarized laser pulse. Harmonics of the laser field are excited at the elastic electron-ion collisions in plasmas. In the nonrelativistic case only odd harmonics can be excited. The ultrarelativistic limit is considered when both even and odd harmonics are excited with the comparable efficiencies. Drift electron velocities are assumed to be small compared to the quiver electron velocities. It is shown that the harmonic yields do not depend on the instantaneous energy distribution of electrons produced at the multiple ionization on the leading edge of the laser pulse. The harmonic conductivity is a tensor with odd components along the laser polarization and with even components along the direction of propagation of the laser pulse. This conductivity tensor has been derived analytically in the ultrarelativistic limit. Possible observation of even harmonics is discussed with respect to the Weibel effect in laser plasmas.
已经推导了由强线偏振激光脉冲产生的多电荷原子离子的相对论等离子体的高次谐波产率。激光场的谐波是在等离子体中的弹性电子 - 离子碰撞中激发的。在非相对论情况下，只能激发奇次谐波。当偶次谐波和奇次谐波以相当的效率被激发时，考虑了超相对论极限。假设漂移电子速度与颤动电子速度相比很小。结果表明，谐波产率不依赖于在激光脉冲前沿多次电离产生的电子的瞬时能量分布。谐波电导率是一个张量，其沿激光偏振方向具有奇数分量，沿激光脉冲传播方向具有偶数分量。这个电导率张量已在超相对论极限下通过解析方法推导出来。关于激光等离子体中的韦贝尔效应，讨论了偶次谐波的可能观测情况。
