Laser-wake field accelerators (LWFAs) are potential candidates to produce intense relativistic electron beams to drive compact free electron lasers (FELs) in VUV and X-ray regions. In High-Field Physics and Ultrafast Technology Laboratory at National Central University (NCU), an LWFA is being developed to produce a 250 MeV high-brightness electron beam by their 100-TW laser system. An FEL seeded by a 266-nm UV laser is under design to generate extreme ultraviolet (EUV) radiation. The initial phase of the project is to develop a beam energy modulator through the interaction of the LFWA-produced electron beam with the 266-nm seed laser in a 10-period planar undulator of 35-mm period length. An electron beamline has been designed based on linear optics to deliver the intense electron pulse from LWFA to the undulator and focus properly. However, due to the large energy spread of the beam, chromatic effects on beam transportation may be severe. In this work, we perform a detailed simulation of the LWFA FEL from experimental data of the NCU LWFA electron source. A 6D phase space analysis of multi-particle dynamics using IMPACT code [1] is to determine how significant the effects of beam energy spread on beam properties along the beamline are. The electron beam is then transferred to GENESIS [2] and Puffin [3] to see the laser beam interaction in the undulator. Further study of the HGHG scheme is evaluated using both FEL codes to see the influence of ultra-short electron bunch.

Laser-wake field accelerators (LWFAs) are potential candidates to produce intense relativistic electron beams to drive compact free electron lasers (FELs) in VUV and X-ray regions. In High-Field Physics and Ultrafast Technology Laboratory at National Central University (NCU), an LWFA is being developed to produce a 250 MeV high-brightness electron beam by their 100-TW laser system. An FEL seeded by a 266-nm UV laser is under design to generate extreme ultraviolet (EUV) radiation. The initial phase of the project is to develop a beam energy modulator through the interaction of the LFWA-produced electron beam with the 266-nm seed laser in a 10-period planar undulator of 35-mm period length. An electron beamline has been designed based on linear optics to deliver the intense electron pulse from LWFA to the undulator and focus properly. However, due to the large energy spread of the beam, chromatic effects on beam transportation may be severe. In this work, we perform a detailed simulation of the LWFA FEL from experimental data of the NCU LWFA electron source. A 6D phase space analysis of multi-particle dynamics using IMPACT code [1] is to determine how significant the effects of beam energy spread on beam properties along the beamline are. The electron beam is then transferred to GENESIS [2] and Puffin [3] to see the laser beam interaction in the undulator. Further study of the HGHG scheme is evaluated using both FEL codes to see the influence of ultra-short electron bunch.

Velocity bunching, sometimes called rectilinear rf bunch compression, is a common technique to generate femtosecond MeV electron bunches from a photoinjector system. Such ultrashort beam can be used to generate coherent THz radiations, in particular, coherent undulator radiation (CUR). However, beam properties such as beamsize, transverse emittance, bunch length and energy spread after bunch compression have significant effects on angular and spectral distributions of CUR. In this study, we perform space charge tracking of electron beam in the NSRRC photoinjector when its booster linac being operated near zero crossing phase in rf bunch compression and the resultant electron distribution of the output beam is then used for calculation of incoherent and coherent undulator radiation from a 10-cm period planar undulator by an algorithm based on Lienard-Wiechart potential. We also compared the radiation properties for cases of multiple bunch and single bunch operation with the same total charge.