- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Retaining 3D Laser Pulse Shape at Sum Frequency Generation Processes
摘要： Modern photoinjectors require to use 3D profiled laser pulses for irradiation of cathode surface. The pulses make it possible to control a space-charge distribution of generated electron bunches and, in particular, to form electron bunches with cylindrical and 3D ellipsoidal shapes. Spatial light modulators (SLM) [1,2] and profiled volume Bragg gratings [3] can be used for control 3D intensity distribution of linearly chirped broadband infrared laser pulses. But, the widely used in photoinjectors Cs2Te photocathodes have the highest efficiency in UV spectral range. So, the important task is to transform the profiled 3D (x,y,t) infrared pulses to visible and UV regions with high energy conversion efficiency and preserving 3D intensity distribution. It can be done with help of second, fourth and third harmonic generation (SHG, FHG, THG) processes at low group velocity mismatch of the interacted pulses. The control of the group velocities can be done by a creation of amplitude tilt or angular chirp. Here we present results of numerical simulations of SHG, FHG and noncollinear THG processes implemented for laser pulses with central wavelength 744 nm, 6 nm spectral width (FWHM) and pulse duration 15 ps (FWHM). The initial fundamental pulse has ellipsoidal 3D shape with linear growth intensity in time.
关键词： energy conversion efficiency,3D laser pulse shape,sum frequency generation,harmonic generation,photoinjectors
更新于2025-09-16 10:30:52
-
Child-Langmuir law for photoinjectors
摘要： The space-charge ?eld at the cathode limits the current density extracted from particle sources such as photoinjectors. For a long time, the maximum current has been estimated by using the classical Child-Langmuir law, which is derived with an assumption inconsistent with the conditions of modern laser-driven electron guns. Here, we introduce a theoretical model that accurately accounts for space-charge effects in transversely con?ned particle beams emerging from photocathodes. The model enables us to (i) determine the maximum current density extractable from the photocathode for an arbitrary cathode radius, (ii) reveal its dependence on the transverse pro?le of the particle beam, and (iii) predict its upper limit for structured beams such as the ones produced by surface-plasmon resonance-enhanced photocathodes.
关键词： photocathodes,space-charge effects,Child-Langmuir law,photoinjectors,surface-plasmon resonance
更新于2025-09-09 09:28:46