Accurate modelling of charged particle beams in linear accelerators

Gjonaj, Erion; Lau, Thomas; Schnepp, Sascha; Wolfheimer, Felix; Weiland, Thomas

doi:10.1088/1367-2630/8/11/285

Cited by 26 publications

(46 citation statements)

References 20 publications

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“…To see how good this approximation is, we have performed numerical, time-domain calculations using the program CST PS, both for an example with the beam on axis between two dechirper plates, and for an example with the beam passing by a single plate. For the case of two dechirper plates, the accuracy of CST PS simulations was verified by cross-checking with results using the wakefield code PBCI [14]. Since the bunches are short (z rms ∼ 20 μm), the catch-up distance [z cu ∼ a 2 =ð2σ z Þ] is large (on the order of cm's).…”

Section: Numerical Time-domain Comparisonsmentioning

confidence: 99%

“…We thus expect our results to underestimate the Joule power losses. Finally, we test the accuracy of these calculations, by performing numerical simulations using the timedomain Maxwell equation solver in CST PARTICLE STUDIO (PS) [13], and also (for verification purposes) with the program PBCI [14]. These calculations are themselves quite challenging, since a fine mesh is needed to resolve the short bunch, and runs need to be performed over a large mesh domain for a relatively long time.…”

Section: Introductionmentioning

confidence: 99%

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Joule heating in a flat dechirper

Bane

Stupakov

Gjonaj

2017

Phys. Rev. Accel. Beams

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We perform Joule power loss calculations for a flat dechirper. We consider the configurations of the beam on-axis between the two plates-for chirp control-and for the beam especially close to one platefor use as a fast kicker. Our calculations use a surface impedance approach, one that is valid when corrugation parameters are small compared to aperture (the perturbative parameter regime). We find that most of the wake power lost by the beam is radiated out to the sides of the plates. For the case of the beam passing by a single plate, we derive an analytical expression for the broadband impedance. Our analytical results are also tested by numerical, time-domain simulations. While our theory can be applied to the LCLS-II dechirper with large gaps, for the nominal apertures we are not in the perturbative regime. With input from computer simulations, we estimate the Joule power loss for nominal apertures (assuming bunch charge of 300 pC, repetition rate of 100 kHz) is 21 W=m for the case of two plates, and 24 W=m for the case of a single plate.

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Section: Numerical Time-domain Comparisonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Joule heating in a flat dechirper

Bane

Stupakov

Gjonaj

2017

Phys. Rev. Accel. Beams

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“…Discretizations of Maxwell's equations using the Discontinuous Galerkin Method have been obtained among others in [7,8,9,10]. We will follow the framework and notation described in our previous work [26], which makes use of hexahedral meshes and modal basis functions as introduced in [10].…”

Section: Discretization Of Maxwell's Equationsmentioning

confidence: 99%

“…[5,6,7] and references therein). Concerning Maxwell's equations in time-domain, the DGM has been studied in particular in [7,8,9,10]. The latter two make use of hexahedral meshes, which allow for a computationally more efficient implementation [11].…”

Section: Introductionmentioning

confidence: 99%

Error-driven dynamicalhp-meshes with the Discontinuous Galerkin Method for three-dimensional wave propagation problems

Schnepp¹

2014

Journal of Computational and Applied Mathematics

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An hp-adaptive Discontinuous Galerkin Method for electromagnetic wave propagation phenomena in the time-domain is proposed. The method is highly efficient and allows for the first time the adaptive full-wave simulation of large, time-dependent problems in three-dimensional space. Refinement is performed anisotropically in the approximation order p and the mesh step size h regardless of the resulting level of hanging nodes. For guiding the adaptation process a variant of the concept of reference solutions with largely reduced computational costs is proposed. The computational mesh is adapted such that a given error tolerance is respected throughout the entire time-domain simulation.

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“…The method introduces equivalent charge r ( ) ρ and current J r ( ) densities, and projects them into the computational grid. It is further used to model RF accelerators and guns [37]. Nonetheless, there are several restrictions to the algorithm which makes it not suitable for problems involving ultrafast field variations and tiny charge distributions [38].…”

Section: Introductionmentioning

confidence: 99%

Field-based DGTD/PIC technique for general and stable simulation of interaction between light and electron bunches

Fallahi¹,

Kärtner²

2014

J. Phys. B: At. Mol. Opt. Phys.

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We introduce a hybrid technique based on the discontinuous Galerkin time domain (DGTD) and the particle in cell (PIC) simulation methods for the analysis of interaction between light and charged particles. The DGTD algorithm is a three-dimensional, dual-field and fully explicit method for efficiently solving Maxwell equations in the time domain on unstructured grids. On the other hand, the PIC algorithm is a versatile technique for the simulation of charged particles in an electromagnetic field. This paper introduces a novel strategy for combining both methods to solve for the electron motion and field distribution when an optical beam interacts with an electron bunch in a very general geometry. The developed software offers a complete and stable numerical solution of the problem for arbitrary charge and field distributions in the time domain on unstructured grids. For this purpose, an advanced search algorithm is developed for fast calculation of field data at charge points and for later importing to the PIC simulations. In addition, we propose a field-based coupling between the two methods resulting in a stable and precise time marching scheme for both fields and charged particle motion. To benchmark the solver, some examples are numerically solved and compared with analytical solutions. Eventually, the developed software is utilized to simulate the field emission from a flat metal plate and a silicon nano-tip. In the future, we will use this technique for the simulation and design of ultrafast compact x-ray sources.

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Accurate modelling of charged particle beams in linear accelerators

Cited by 26 publications

References 20 publications

Joule heating in a flat dechirper

Joule heating in a flat dechirper

Error-driven dynamicalhp-meshes with the Discontinuous Galerkin Method for three-dimensional wave propagation problems

Field-based DGTD/PIC technique for general and stable simulation of interaction between light and electron bunches

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