52 research outputs found
Studies on charge production from Cs2Te photocathodes in the PITZ L-band normal conducting radio frequency photo injector
This paper discusses the behavior of electron bunch charge produced in an
L-band normal conducting radio frequency cavity (RF gun) from Cs2Te
photocathodes illuminated with ps-long UV laser pulses when the laser
transverse distribution consists of a flat-top core with Gaussian-like decaying
halo. The produced charge shows a linear dependence at low laser pulse energies
as expected in the quantum efficiency limited emission regime, while its
dependence on laser pulse energy is observed to be much weaker for higher
values, due to space charge limited emission. However, direct plug-in of
experimental parameters into the space charge tracking code ASTRA yields lower
output charge in the space charge limited regime compared to measured values.
The rate of increase of the produced charge at high laser pulse energies close
to the space charge limited emission regime seems to be proportional to the
amount of halo present in the radial laser profile since the charge from the
core has saturated already. By utilizing core + halo particle distributions
based on measured radial laser profiles, ASTRA simulations and semi-analytical
emission models reproduce the behavior of the measured charge for a wide range
of RF gun and laser operational parameters within the measurement
uncertainties.Comment: 15 pages, 16 figures, 2 table
Radiation Generation with an Existing Demonstrator of an Energy Recovery Continuous Wave Superconducting RF Accelerator
Over the past decades, many accelerator laboratories have put much effort into the development of compact energy recovery linac ERL demonstrators to verify various physical and technical aspects of the generation, acceleration, transport and energy recovery of high brightness and high average current electron beams in a superconducting radio frequency SRF linear accelerator. Beyond these goals, the ERL demonstrator also offers unique opportunities to study novel schemes for THz and X ray radiation generation. In this paper, we discuss feasible options for schemes generating THz and X ray radiation at low energy continuous wave CW SRF ERL demonstrators such as the bERLinPro accelerato
Report on Gun Conditioning Activities at PITZ in 2013
Recently three RF guns were prepared at the Photo Injector Test Facility at DESY, location Zeuthen PITZ for their subsequent operation at FLASH and the European XFEL. The gun 3.1 is a previous cavity design and is currently installed and operated at FLASH, the other two guns 4.3 and 4.4 were of the current cavity design and are dedicated to serve for the start up of the European XFEL photo injector. All three cavities had been dry ice cleaned prior their conditioning and hence showed low dark current levels. The lowest dark current level as low as 60 amp; 956;A at 65MV m field amplitude has been observed for the gun 3.1. This paper reports in details about the conditioning process of the most recent gun 4.4. It informs about experience gained at PITZ during establishing of the RF conditioning procedure and provides a comparison with the other gun cavities in terms of the dark currents. It also summarizes the major setup upgrades, which have affected the conditioning processes of the cavitie
ProtonâRadiation Tolerant AllâPerovskite Multijunction Solar Cells
Funder: European Research Council; Id: http://dx.doi.org/10.13039/501100000781Funder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266Funder: European Union's Horizon 2020Abstract: Radiationâresistant but costâefficient, flexible, and ultralight solar sheets with high specific power (W gâ1) are the âholy grailâ of the new space revolution, powering private space exploration, lowâcost missions, and future habitats on Moon and Mars. Herein, this study investigates an allâperovskite tandem photovoltaic (PV) technology that uses an ultrathin active layer (1.56 ”m) but offers high power conversion efficiency, and discusses its potential for highâspecificâpower applications. This study demonstrates that allâperovskite tandems possess a high tolerance to the harsh radiation environment in space. The tests under 68 MeV proton irradiation show negligible degradation (22%. Using high spatial resolution photoluminescence (PL) microscopy, it is revealed that defect clusters in GaAs are responsible for the degradation of current spaceâPV. By contrast, negligible reduction in PL of the individual perovskite subcells even after the highest dose studied is observed. Studying the intensityâdependent PL of bare lowâgap and highâgap perovskite absorbers, it is shown that the VOC, fill factor, and efficiency potentials remain identically high after irradiation. Radiation damage of allâperovskite tandems thus has a fundamentally different origin to traditional space PV
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