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@PHDTHESIS{GonzalezCaminal:480259,
author = {Gonzalez Caminal, Pau},
othercontributors = {D'Arcy, Richard and Hillert, Wolfgang},
title = {{T}ime-{R}esolved {P}hase-{S}pace {C}haracterisation of
{P}lasma-{W}akefield-{A}ccelerated {E}lectrons at
{FLASHF}orward},
school = {Universität Hamburg},
type = {Dissertation},
address = {Hamburg},
publisher = {Verlag Deutsches Elektronen-Synchrotron DESY},
reportid = {PUBDB-2022-03578, DESY-THESIS-2022-014},
series = {DESY-THESIS},
pages = {262},
year = {2022},
note = {Dissertation, Universität Hamburg, 2022},
abstract = {A plasma can sustain electric fields orders of magnitude
larger than those attainable with the conventional
radio-frequency (RF) technology typically used in particle
accelerators, which are limited to ∼ 100 MV/m due to
electrical breakdowns occurring at the metallic boundary of
the accelerating structures. In a particle-beam-driven
plasma-wakefield accelerator (PWFA), a charge-density wake
sustaining field gradients in excess of GV/m is driven by
the passage of a relativistic high-intensity particle bunch
through a plasma. By harnessing the gradientsof the wake,
particles trailing behind the wakefield-driving bunch can be
accelerated to GeV energies over meter distances, thus
enabling a drastic reduction of the size of
acceleratorcomponenents and, consequently, potentially
reducing the costs of future accelerator facilities. Despite
this promise, however, for PWFA to be a viable technology,
the quality of theaccelerated bunches must match that
achieved by RF-based state-of-the-art FEL linacs and
particle colliders. Even though theoretical predictions
suggest that PWFA schemes are capable of producing
electric-field profiles with properties sufficient to
preserve the longitudinal-phase-space structure of the
accelerating beam, direct experimental demonstration has not
yet been achieved.In the work presented in this thesis the
diagnostic capabilities of a novel X-band transverse
deflection structure (TDS)—featuring femtosecond
resolution and a variablepolarisation of the streaking
field—are exploited to investigate two mechanisms enabling
the preservation of the energy spread of electron beams
accelerated in a nonlinear plasma wake: optimal beam loading
to preserve the correlated energy spread and a fully
evacuated ion column to preserve the uncorrelated energy
spread. By directly observing the longitudinal phase space
of 1-GeV bunches accelerated 44 MeV in a nonlinear plasma
wake, experiments performed at the FLASHForward facility
(DESY, Hamburg) demonstrate that the longitudinal
accelerating gradients are transversely homogeneous to
within 0.8 $\%$ (1.5 $\%)$ at an interval of confidence of
68 $\%$ (95 $\%)$ and show variable amounts of beam loading
depending on the exact shape of the current profile of the
driver-trailing-bunch pair. The results presented in this
work experimentally demonstrate the predicted suitability of
PWFA for future applications requiring the preservation of
high longitudinal beam quality. Furthermore, a
reconstruction of the beam-plasma interaction in a
particle-in-cell code has been accomplished, which
illustrates the extreme sensitivity of the PWFA acceleration
process to the phase-space distribution of the incoming
beams. These achievements suggest that, while PWFA is
capable of producing the desired field geometries, an
improved control over the production of
driver-trailing-bunch pairs will be required to demonstrate
stable and quality-preserving acceleration at higher energy
gains.},
cin = {$HH_FH_FTX_AS$ / MPA2},
cid = {$I:(DE-H253)HH_FH_FTX_AS-20210421$ /
I:(DE-H253)MPA2-20210408},
pnm = {621 - Accelerator Research and Development (POF4-621) /
PHGS, VH-GS-500 - PIER Helmholtz Graduate School
$(2015_IFV-VH-GS-500)$},
pid = {G:(DE-HGF)POF4-621 / $G:(DE-HGF)2015_IFV-VH-GS-500$},
experiment = {EXP:(DE-H253)FLASHForward-20150101},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
doi = {10.3204/PUBDB-2022-03578},
url = {https://bib-pubdb1.desy.de/record/480259},
}