Mirzaie Mohammad, Hafz Nasr A M, Li Song, Liu Feng, He Fei, Cheng Ya, Zhang Jie
Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
Rev Sci Instrum. 2015 Oct;86(10):103502. doi: 10.1063/1.4931780.
An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.
在一个典型的激光等离子体尾场加速实验中，对来自氦气、氮气和氖气喷流等离子体的电子束产额（电荷量）进行了研究。通过将荧光屏上电子束强度分布成像到电荷耦合器件中来进行电荷测量，该电荷耦合器件已与积分电流互感器进行了交叉校准。研究了上述气体的电子束电荷量对激光和等离子体条件的依赖性。我们发现，在低Z值气体喷流靶中，激光驱动的尾场加速通常会产生高质量且准直良好的电子束，产额适中，在10 - 100 pC的水平。另一方面，在较高密度下从高Z值气体中观察到的丝状电子束产额要高得多。在氮气喷流靶中清晰地观察到了团簇形成的证据，在那里我们获得了约1.7 nC的最高电子束电荷量。那些强电子束将有利于通过轫致辐射或逆散射过程产生明亮的X射线、伽马射线辐射以及高能正电子的应用。
