空泡机制产生 betatron X 射线辐射的数值模拟

摘要

针对SILEX钛宝石激光器参数,采用PIC数值模拟程序VORPAL对激光尾波场加速进行了模拟,得到了电子轨迹及能量数据,进而通过理论计算得到了空泡机制下X射线辐射特性.结果表明,空泡机制下高能电子在空泡中做betatron振荡且多数电子被加速到170 MeV左右；加速能量较低的电子(约100MeV),其辐射谱为临界能量约3 keV的类同步辐射谱,发散角约为8 mrad,而能量较高的电子(约170 MeV)对应的光子临界能量约为10 keV.%To find a solution for the high brightness, ultra-short pulse X-ray source, the betatron X-ray mechanism was studied. It is based on the interactions which generate the laser wake field acceleration (LWFA), between the ultra-intense short laser and the plasma. These accelerated electrons make betatron oscillations in the transverse fields of the bubble and emit high brightness and ultra-short X-ray pulses (about fs). Also, this kind of source has the advantages of small size, low cost. The numerical calculations of the emission of the betatron X-rays were carried out with 2D-PIC simulations and the data processing software. Synchrotron spectra with critical energy of 3 keV and 10 keV which are radiated by the lower energy electrons (about 100 MeV) and the higher energy electrons (about 170 MeV) respectively, are reported and the emission is confined to a small angle of about 8 mrad, which has a good agreement with the theoretical results.