Publications by authors named "Jochen Teichert"
Article Synopsis
- This study investigates how residual carbon on p-GaN photocathodes affects their quantum efficiency, emphasizing the importance of a clean surface for achieving negative electron affinity.
- The research utilizes an in-situ X-ray photoelectron spectrometer (XPS) to monitor changes on the photocathode surface during cleaning, activation, and degradation processes.
- Despite the presence of carbon and oxygen contaminants from the manufacturing process, activating p-GaN with cesium allows for the formation of negative electron affinity and reveals the role of cesium carbide in photocathode performance degradation.
Article Synopsis
- Accelerator scientists require photocathodes with high quantum efficiency (QE) and durability; p-GaN photocathodes, enhanced with cesium, have emerged as promising candidates due to their negative electron affinity surface.* -
- In this study, p-GaN samples were cleaned and activated in an ultra-high vacuum (UHV) chamber, with subsequent analysis of their performance and surface characteristics using various microscopic techniques.* -
- Results indicate that both wet chemical and thermal cleaning processes affect the cathodes' quality, but high QE and long storage life can be achieved at lower cleaning temperatures.*
Multiple optical harmonic generation-the multiplication of photon energy as a result of nonlinear interaction between light and matter-is a key technology in modern electronics and optoelectronics, because it allows the conversion of optical or electronic signals into signals with much higher frequency, and the generation of frequency combs. Owing to the unique electronic band structure of graphene, which features massless Dirac fermions, it has been repeatedly predicted that optical harmonic generation in graphene should be particularly efficient at the technologically important terahertz frequencies. However, these predictions have yet to be confirmed experimentally under technologically relevant operation conditions.
View Article and Find Full Text PDFA superconducting radio frequency (SRF) photoelectron injector is currently under construction by a collaboration of BESSY, DESY, FZD, and MBI. The project aims at the design and setup of a continuous-wave SRF injector including a diagnostics beamline for the ELBE free electron laser (FEL) and to address R&D issues on low emittance injectors for future light sources such as the BESSY FEL. Of critical importance for the injector performance is the control of the electron beam parameters.
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