Abstract
Dielectric gratings are already used in Dielectric Laser Acceleration due to their high damage thresholds at high acceleration gradients. When an electron bunch passes close to one of these ...gratings, it emits radiation, and the features of this radiation will be dependent upon the beam position relative to the grating, the bunch charge, and the bunch length. A compact high-resolution diagnostics device will be developed that consists of multiple gratings with different periods; these types of devices are required for the accurate operation of future compact accelerators which are currently undergoing development and testing. ARES linac at DESY is able to provide sub-fs electron bunches and has a range of high-resolution diagnostic devices installed, such as the PolariX Transverse Deflecting Structure, which will allow for performance verification of a new diagnostic. The electron bunches can be altered, allowing for the measurement and analysis of the emitted radiation for different bunch lengths and charges. This work will present the current progress in this area, including the presentation and discussion of simulations, and a discussion of the planned experiments at ARES.
Emerging high-frequency accelerator technology in the terahertz regime is promising for the development of compact high-brightness accelerators and high resolution–power beam diagnostics. One ...resounding challenge when scaling to higher frequencies and to smaller structures is the proportional scaling of tolerances which can hinder the overall performance of the structure. Consequently, characterizing these structures is essential for nominal operation. Here, we present a novel and simple self-calibration technique to characterize the dispersion relation of integrated hollow THz waveguides. The developed model is verified in simulation by extracting dispersion characteristics of a standard waveguide a priori known by theory. The extracted phase velocity is in good agreement with the true value. In experiments, the method demonstrates its ability to measure dispersion characteristics of nonstandard waveguides embedded with their couplers with an accuracy due to systematic errors of≈0.5%. Equipped with dielectric lining, the metallic waveguides act as slow wave structures, and the dispersion curves are compared without and with dielectric. A phase synchronous mode, suitable for transverse deflection, is found at 275 GHz.
Abstract
Methodical studies to improve the existing e-beam Longitudinal Phase Space (LPS) tomography were performed at the Photo Injector Test facility at DESY in Zeuthen. Proof-of-principle ...simulations were done to address some core concerns e.g. booster phase range, space charge effects and noisy artefacts in results. Phase advance analysis was done with the help of an analytical model that determined the booster phase range and step size. A slit was introduced before the booster to truncate the beam and reduce space charge forces. The reconstruction method adopted was image space reconstruction algorithm owing to its assurance of non-negative solution. An initial scientific presumption of LPS from low energy momentum measurements was established to reduce artefacts in the phase space. This paper will explain the proof-of-principle simulations highlighting the key aspects to obtain accurate results. Reconstructed LPS for different experimental cases will be presented to demonstrate the diagnostic capability.
We propose a new beam diagnostics method to reconstruct the phase space of charged particle bunches in five dimensions, which consist of the horizontal and vertical positions and divergences as well ...as the time axis. This is achieved by combining a quadrupole-based transverse phase-space tomography with the adjustable streaking angle of a polarizable X-band transverse deflection structure. We demonstrate with detailed simulations that the method is able to reconstruct various complex phase-space distributions and that the quality of the reconstruction depends on the number of input projections. This method allows for the identification and visualization of previously unnoticed detailed features in the phase-space distribution and can thereby be used as a tool toward improving the performance of particle accelerators or performing more accurate simulation studies. Published by the American Physical Society 2024
Sensitivity of EEHG simulations to dynamic beam parameters Samoilenko, D; Hillert, W; Pannek, F ...
13th International Particle Accelerator Conference, IPAC 2022,Bangkok, Thailand,2022-06-12 - 2022-06-17,
01/2023, Letnik:
2420, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Abstract
Currently, the Free electron laser user facility FLASH at DESY is undergoing a significant upgrade involving the complete transformation of one of its beamlines to allow external seeding. ...With the Echo-Enabled Harmonic Generation (EEHG) seeding method, we aim for the generation of fully coherent XUV and soft X-ray pulses at wavelengths down to 4 nm. The generated FEL radiation is sensitive to various electron beam properties, e.g., its energy profile imprinted either deliberately or by collective effects such as Coherent Synchrotron Radiation (CSR). In dedicated particle tracking simulations, one usually makes certain assumptions concerning the beam properties and the collective effects to simplify implementation and analysis. Here, we estimate the influence of some of the common assumptions made in EEHG simulations on the properties of the output FEL radiation, using the example of FLASH and its proposed seeding beamline. We conclude that the inherent properties of the FLASH1 beam, namely the negatively chirped energy profile, has dominant effect on the spectral intensity profile of the radiators output compare to that of the CSR induced chirp.
Abstract
Development of an accelerator-based tunable THz source prototype for pump-probe experiments at the European XFEL is ongoing at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The ...proof-of-principle experiments on the THz SASE FEL are performed utilizing the LCLS-I undulator (on loan from SLAC) installed in the PITZ beamline. The first lasing at a center wavelength of 100 μm was observed in the summer of 2022. The lasing of the narrowband THz source was achieved using an electron beam with an energy of ∼17 MeV and a bunch charge up to several nC. Optimization of beam transport and matching resulted in the measurement of THz radiation with a pulse energy of tens of μJ, measured with pyroelectric detectors. The THz FEL gain curves were measured by means of specially designed short coils along the undulator. The results of the first characterization of the THz source at PITZ will be presented.
Echo-enabled harmonic generation (EEHG) is a promising technique for seeded free electron lasers (FELs) not only to go down to wavelengths of 4 nm but also to simplify the schemes that are currently ...used to achieve a similar wavelength range (double cascade HGHG). Thus a study optimizing the EEHG performance in the wavelength range from 60 to 4nm has been performed. The more critical working point, at 4 nm, is here analyzed in terms of seed laser stability for two different seed laser frequencies: visible and UV.
The η-carbon potential at low meson momenta Nanova, M.; Friedrich, S.; Metag, V. ...
The European physical journal. A, Hadrons and nuclei,
2018/10, Letnik:
54, Številka:
10
Journal Article
Recenzirano
Odprti dostop
.
The production of
η
mesons in coincidence with forward-going protons has been studied in photon-induced reactions on
12
C and on a liquid hydrogen (LH
2
) target for incoming photon energies of ...1.3-2.6 GeV at the electron accelerator ELSA. The
η
mesons have been identified via the
η
→
π
0
π
0
η
→
6
γ
decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF
2
array at polar angles of
2
∘
≤
θ
p
≤
11
∘
. Under these kinematic constraints the
η
mesons are produced with relatively low kinetic energy (
≈
150
MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the
η
-carbon potential at low meson momenta by comparing with collision model calculations of the
η
kinetic energy distribution and excitation function. Fitting the latter data for
η
mesons going backwards in the center-of-mass system yields a potential depth of
V
=
-
(
44
±
16
(
s
t
a
t
)
±
15
(
s
y
s
t
)
)
MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average
η
momenta of
≈
1
.
1
GeV/
c
. Within the experimental uncertainties, there is no indication of a momentum dependence of the
η
-carbon potential. The LH
2
data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for
η
photoproduction off the free proton.
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