124 research outputs found
Beam Dynamics Analysis of Dielectric Laser Acceleration using a Fast 6D Tracking Scheme
A six-dimensional symplectic tracking approach exploiting the periodicity
properties of Dielectric Laser Acceleration (DLA) gratings is presented. The
longitudinal kick is obtained from the spatial Fourier harmonics of the laser
field within the structure, and the transverse kicks are obtained using the
Panofsky-Wenzel theorem. Additionally to the usual, strictly longitudinally
periodic gratings, our approach is also applicable to periodicity chirped
(sub-relativistic) and tilted (deflection) gratings. In the limit of small
kicks and short periods we obtain the 6D Hamiltonian, which allows, for
example, to obtain matched beam distributions in DLAs. The scheme is applied to
beam and grating parameters similar to recently performed experiments. The
paper concludes with an outlook to laser based focusing schemes, which are
promising to overcome fundamental interaction length limitations, in order to
build an entire microchip-sized laser driven accelerator
Transverse decoherence and coherent spectra in long bunches with space charge
The transverse bunch spectrum and the transverse decoherence/recoherence
following an initial bunch offset are important phenomena in synchrotrons and
storage rings, and are widely used for beam and lattice measurements.
Incoherent shifts of the particles betatron frequency and of the synchrotron
frequency modify the transverse spectrum and the bunch decoherence. In this
study we analyze the effects of transverse space charge and of the rf
nonlinearity on the decoherence signals. The transverse bunch decoherence and
the resulting coherent spectra are measured in the SIS18 synchrotron at GSI
Darmstadt for different bunch parameters. Particle tracking simulations
together with an analytical model are used to describe the modifications in the
decoherence signals and in the coherent spectra due to space charge and the rf
bucket nonlinearity.Comment: Submitted on May 7 2012 to Physical Review Special Topics -
Accelerators and Beam
Pulsed Electron Lenses for Space Charge Mitigation
To produce the intense, high-quality hadron beams required by future nuclear
and high-energy physics experiments, synchrotrons need to overcome the most
prominent intensity limitation i.e., space charge. This Letter characterizes
the potential of pulsed electron lenses in detailed 3D tracking simulations,
key to which is a realistic machine and space charge model. The space charge
limit, imparted by betatron resonances, is shown to be increased by up to 50%
using a low symmetric number of electron lenses in application to the FAIR
SIS100 synchrotron. Conceptually, a 100% increase is demonstrated with a larger
number of electron lenses, which is found to rapidly saturate near the
theoretical 2D limit.Comment: 6 pages, 5 figure
Analytic Modeling, Simulation and Interpretation of Broadband Beam Coupling Impedance Bench Measurements
In the first part of the paper a generalized theoretical approach towards
beam coupling impedances and stretched-wire measurements is introduced. Applied
to a circular symmetric setup, this approach allows to estimate the systematic
measurement error due to the presence of the wire. Further, the interaction of
the beam or the TEM wave, respectively, with dispersive material such as
ferrite is discussed. The dependence of the obtained impedances on the
relativistic velocity is investigated and found as material property
dependent. The conversion formulas for the TEM scattering parameters from
measurements to impedances are compared with each other and the analytical
impedance solution. In the second part of the paper the measurements are
compared to numerical simulations of wakefields and scattering parameters. In
practice, the measurements have been performed for the circularly symmetric
example setup. The optimization of the measurement process is discussed. The
paper concludes with a summary of systematic and statistic error sources for
impedance bench measurements and their diminishment strategy
Modeling of a Liquid Leaf Target TNSA Experiment using Particle-In-Cell Simulations and Deep Learning
Liquid leaf targets show promise as high repetition rate targets for
laser-based ion acceleration using the Target Normal Sheath Acceleration (TNSA)
mechanism and are currently under development. In this work, we discuss the
effects of different ion species and investigate how they can be leveraged for
use as a possible laser-driven neutron source. To aid in this research, we
develop a surrogate model for liquid leaf target laser-ion acceleration
experiments, based on artificial neural networks. The model is trained using
data from Particle-In-Cell (PIC) simulations. The fast inference speed of our
deep learning model allows us to optimize experimental parameters for maximum
ion energy and laser-energy conversion efficiency. An analysis of parameter
influence on our model output, using Sobol and PAWN indices, provides deeper
insights into the laser-plasma system
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