| Paper | Title | Page |
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| TUPRB018 | Design Studies of a Proof-of-Principle Experiment on THz SASE FEL at PITZ | 1713 |
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| A free-electron laser based THz source is undergoing design studies at the Photo Injector Test facility at DESY in Zeuthen (PITZ). It is considered as a prototype for pump-probe experiments at the European XFEL, benefiting from the fact that the electron beam from the PITZ facility has an identical pulse train structure as the XFEL pulses. In the proposed proof-of-principle experiment, the electron beam (up to 4 nC bunch charge and 200 A peak current) will be accelerated to 16-22 MeV/c to generate SASE radiations in an LCLS-I undulator in the THz range between 60 and 100 µm with an expected energy of up to ~1 mJ/pulse. In this paper, we report our simulations on the optimization of the photo-injector and the design of the transport and matching beamline. Experimental investigations on the generation, characterization and matching of the high charge beam in the existing 22-m-long beamline will also be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB018 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS012 | Emittance Reduction of RF Photoinjector Generated Electron Beams By Transverse Laser Beam Shaping | 1958 |
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| Laser pulse shaping is one of the key elements to generate low emittance electron beams with RF photoinjectors. Ultimately high performance can be achieved with ellipsoidal laser pulses, but 3-dimensional shaping is challenging. High beam quality can also be reached by simple transverse pulse shaping, which has demonstrated improved beam emittance compared to a transversely uniform laser in the ‘pancake’ photoemission regime. In this contribution we present the truncation of a Gaussian laser at a radius of approximately one σ in the intermediate (electron bunch length directly after emission about the same as radius) photoemission regime with high acceleration gradients (up to 60 MV/m). This type of electron bunch is used e.g. at the European XFEL and FLASH free electron lasers at DESY, Hamburg site and is being investigated in detail at the Photoinjector Test facility at DESY in Zeuthen (PITZ). Here we present ray-tracing simulations and experimental data of a laser beamline upgrade enabling variable transverse truncation. Initial projected emittance measurements taken with help of this setup are shown, as well as supporting beam dynamics simulations. Additional simulations show the potential for substantial reduction of slice emittance at PITZ. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS012 | |
| About • | paper received ※ 24 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS014 | SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS | 1964 |
| SUSPFO016 | use link to see paper's listing under its alternate paper code | |
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| In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS014 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| THPGW016 | Overview and Prospects of Plasma Wakefield Acceleration Experiments at PITZ | 3612 |
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| The Photo Injector Test Facility at DESY in Zeuthen (PITZ) carries out studies of beam-driven plasma wakefield acceleration (PWFA). The facility possesses a flexible photocathode laser beam shaping system and a variety of diagnostics including a high-resolution dipole spectrometer and an rf deflector which enables the observation of the longitudinal phase space of electron beams after their passage through a plasma. Two plasma sources are available: a gas discharge plasma cell and a photoionized lithium vapor plasma cell. Studies at PITZ include investigations of the self-modulation instability of long electron beams and the high transformer ratio, i.e., the ratio between the maximum accelerating field behind the drive beam and the decelerating field within the beam. This overview includes the experimental results and plans for future experiments. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW016 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019 | |
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| THPGW017 | Self-Modulation Instability of Electron Beams in Plasma Channels of Variable Length | 3616 |
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The self-modulation instability (SMI) of long (in respect to the plasma wavelength) charged particle beams passing through plasma enables the use of currently existing high energy charged particle beams as drivers for plasma wakefield accelerators. At the Photo Injector Test facility at DESY in Zeuthen (PITZ) the SMI of electron beams is studied *, **. An enhanced experimental setup includes a plasma channel of variable length which allows to investigate in details the development stages of the SMI by measuring the instability growth rate and phase velocity as a function of propagation distance in the plasma. In this contribution we present the experimental setup improvements, first measurement results and supporting beam dynamics simulations.
* M. Gross, et al., Phys. Rev. Lett., vol. 120, p. 144802, 2018. ** G. Loisch, et al., Plasma Physics and Controlled Fusion, vol. 61(4), p. 045012, 2019 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW017 | |
| About • | paper received ※ 11 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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