| Paper | Title | Page |
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MOPB011 |
Bunch Adaptive Shaping Based on Spatial Light Modulator | |
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| The second generation of direct current-superconducting radio frequency (DC-SRF-¿) photocathode electron gun drive laser system utilizes a liquid crystal-spatial light modulator (SLM) to generate high-fidelity shaped laser beams with arbitrary spatial profiles by the polarization-mask shaping method. These adaptive lasers are then transmitted to the photocathode of photocathode electron gun can generate electron bunches with special spatial distributions. The electron beams distribution can be produced highly similar to the laser, where space charge is negligible. Based on the electron beams imaging, this work proposes a method for rapidly quantum efficiency (QE) mapping under low-charge conditions, and then using a feedback method by adjusting laser distribution to produce more uniform electron beam. This method can correct irregularities caused by both laser distribution and spatial QE. At present, the experiments have been preliminarily carried out on the DC-SRF-II of Peking University. | ||
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MOPB013 |
Correction of Electron Beam Aberration Due to Multipole Fields in a Continuous-Wave Photocathode Gun | |
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| Continuous-wave photocathode guns can deliver electron beams with high repetition rates and high average currents, but their achievable accelerating gradients and cathode fields are relatively low. This leads to a large beam size at the gun exit due to space charge effects, which makes the beam more sensitive to optical aberrations and poses challenges for low-emittance electron beam transmission. This work focuses on the aberration caused by multipole fields. It analyzes the effects of quadrupole, sextupole, octupole and higher order fields on beam shape and transverse emittance, and proposes a beam-based method for rapid characterization and correction of multipole fields. Additionally, an experimental study is being conducted on the DC-SRF-II photocathode gun at Peking University, with corresponding correctors designed for the quadrupole and sextupole fields in the beamline. The experimental results show that the electron beam aberration due to multipole fields can be effectively corrected through appropriate corrector settings, resulting in improved beam symmetry and reduced emittance. | ||
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TUIAA01 |
Commissioning and experimental study of the DC-SRF-II photocathode gun | |
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| The DC-SRF photocathode gun is a distinguished compact MeV electron source capable of generating picosecond to sub-picosecond electron pulses at MHz to 100 MHz repetition rate. With the goals to achieve low-emittance CW operation and to generate high average current electron beam, the second-generation DC-SRF gun, DC-SRF-II, has been developed. Efforts have been made recently to optimize the performance of the gun. In this work, we present the commissioning of the DC-SRF-II gun, with the focus on beam dynamics and related issues. | ||
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