Compton散射对激光等离子体通道天线特性的影响

Influences of Compton scattering on the properties of laser plasma channel antenna

应用多光子非线性Compton散射模型和数值计算方法,研究了激光等离子体通道天线传播和辐射特性,结果表明:随通道周围介质损耗和传输模式阶数的增大,传输模式THnm衰减常数明显增大.这是因散射使通道内外电场和磁场增强,粒子间碰撞频率增大,电场使更多分子电离而吸收更多能量的缘故.随模式阶数增大,电性有耗介质使相移常数明显减小.这是因散射使高阶模式可能存在被耦合电场俘获的缘故.等离子体耦合频率为0.7附近,衰减常数随频率增大而剧烈增大.这是因散射使介质分子发生二、三阶电离,更多电子被耦合电场急剧加速的缘故.随天线长度增加,天线辐射方向图主瓣和副瓣数量、宽度和最大辐射方向发生明显变化.这是因散射使天线频率增大,辐射波长变短,粒子电离几率增大,辐射波能量和频率成分增大的缘故.

By using the model of multi - photon nonlinear Compton scattering and the numerical computing means, the properties of the propagation and radiation of laser plasma channel antenna are studied. The results show that the attenuation constant of the propagation model THnm is clearly increased along the increases of the dielectric loss near the channel and the propagation model step number. The causes are that the electric field and magnetic field in and outside the channel are increased by Compton scattering, the collision frequency between the particle and particle is increased, and even more energies are absorbed by the even molecules ionized by Compton scattering. The phase moving constant is clearly decreased by the electric loss dielectric along the in- creasing model step number. This is dus to the possibility on the capture of the high step model by the coupling electric field. Near 0. 7 coupling plasma frequency, the attenuation constant is acutely increased along the in- creasing frequency. The cause are that the 2nd and 3rd step ionizations of the medium molecule are taken by Compton scattering, and the even more electrons are sharply accelerated by the coupling electric field. The num- bers of the main and vice piece, the widths and the maximum radiation directions in the map of the antenna radi- ation direction are clearly changed along the increasing antenna length. The cause are that because of the scatter- ing, the antenna frequency is creased, the radiation wave length is decreased, the probability particle ionization is increased, and the energy and radiation wave frequency composition are increased.