Perturbation-minimized triangular bunch for high-transformer ratio using a double dogleg emittance exchange beam line

Ha, Gwanghui; Cho, M. H.; Gai, W.; Kim, K. J.; Namkung, W.; Power, John

doi:10.1103/physrevaccelbeams.19.121301

Cited by 26 publications

(22 citation statements)

References 17 publications

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“…The first section consists of a L-band 1.5-cell photoinjector and six standing-wave linacs acting as the acceleration elements. In the second section, the beam is sent to the emittance exchange (EEX) beam line which has the function of exchanging the beam longitudinal space with transverse space [21,22]. The third section is the wakefield generation section which consists of a dielectriclined slab (DLS) as the wakefield accelerating structure.…”

Section: Demonstration Of Mapping Methodsmentioning

confidence: 99%

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Single-shot wakefield measurement system

Gao

Shi

Chen

et al. 2018

Phys. Rev. Accel. Beams

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A new experimental technique for the accurate measurements of wakefields is presented. Knowledge of wakefields is required for many applications ranging from the suppression of wakefields that arise from geometrical discontinuities to the enhancement of wakefields in structure and plasma based wakefield accelerators. In the past, direct measurements of wakefields were done with the drive-witness technique wherein the delay of a short witness beam trailing collinearly behind a high-charge drive beam is scanned over multiple shots and the wakefield is inferred from the energy spectrum of the witness beam. That technique is limited by shot-to-shot jitter, overlap of the drive and witness energy spectrum and the loss of all time-domain information. In this paper, we describe a new technique that overcomes these limitations by measuring the longitudinal phase space of a long witness beam and the drive beam in a single shot. We conclude by presenting experimental results to demonstrate its feasibility using a dielectric structure wakefield accelerator.

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Section: Demonstration Of Mapping Methodsmentioning

confidence: 99%

“…7. The tail of the triangle is not as sharp as in the initial transverse space, which is due to the perturbation of coherent synchrotron radiation [21,25]. The total length of the witness bunch is designed to be longer than one wavelength of wakefield fundamental mode as described in Sec.…”

Section: A Start-to-end Simulation Demonstrationmentioning

confidence: 99%

Single-shot wakefield measurement system

Gao

Shi

Chen

et al. 2018

Phys. Rev. Accel. Beams

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“…Research at the AWA is focused on advanced accelerator concepts, which generally include efforts to improve control, diagnostic instrumentation, and components (e.g., accelerating structures) for future accelerators. Much effort is also dedicated to developing and testing beam line configurations that could be used for beam shaping [35], or future linear colliders [36]. Often, the accelerator settings (e.g., focusing fields for all magnets, cavity phases, cavity accelerating gradients) are adjusted prior to each experiment to achieve custom beam characteristics (e.g., bunch length and transverse sizes).…”

Section: B Validation Of ML Surrogate Modeling Approach For Optimizamentioning

confidence: 99%

Machine learning for orders of magnitude speedup in multiobjective optimization of particle accelerator systems

Edelen¹,

Neveu²,

Frey³

et al. 2020

Phys. Rev. Accel. Beams

101

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High-fidelity physics simulations are powerful tools in the design and optimization of charged particle accelerators. However, the computational burden of these simulations often limits their use in practice for design optimization and experiment planning. It also precludes their use as on-line models tied directly to accelerator operation. We introduce an approach based on machine learning to create nonlinear, fastexecuting surrogate models that are informed by a sparse sampling of the physics simulation. The models are Oð10 6 Þ-Oð10 7 Þ times more computationally efficient to execute. We also demonstrate that these models can be reliably used with multiobjective optimization to obtain orders-of-magnitude speedup in initial design studies and experiment planning. For example, we required 132 times fewer simulation evaluations to obtain an equivalent solution for our main test case, and initial studies suggest that between 330-550 times fewer simulation evaluations are needed when using an iterative retraining process. Our approach enables new ways for high-fidelity particle accelerator simulations to be used, at comparatively little computational cost.

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“…Current methods to produce transversely shaped beams include using a photocathode excited by a patterned drive laser beam [10] and using an intercepting mask on the electron beam [7], [8], [11]. The disadvantages of the mask method include hazardous X-rays, produced when the mask intercepts the beam, beam loss onto the mask of up to 80%, and inconsistency in the beam shape shot-to-shot due to jitter.…”

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confidence: 99%

Shaped Beams from Diamond Field-Emitter Array Cathodes

Andrews

Nichols

Kim

et al. 2020

IEEE Trans. Plasma Sci.

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Diamond field-emitter arrays (DFEAs) are arrays of diamond pyramids with exquisitely sharp tips and micrometerscale bases that produce high current densities. These arrays can be fabricated in arbitrary shapes, ranging from single tips to many millions of tips, so that they produce an inherently shaped electron beam. Each tip emits a modest current, but the large dense array can produce many Amps. We are investigating these cathodes for use in dielectric wakefield accelerators; however, they may also be applicable to vacuum microwave tubes. Recently, shaped beam production and transport have been demonstrated in the 1.3-GHz RF gun at the Argonne Cathode Test Stand at the Argonne National Laboratory. The charge was measured on a Faraday cup and the beam imaged on a YAG screen with peak electric field gradients on the cathode ranging from 12 to 35 MV/m. Three cathode geometries were tested: one 1-mm equilateral triangle with 7-µm base pyramids and 10-µm pitch, one 1-mm equilateral triangle with 10-µm base and 25-µm pitch, and one sparse 5 × 5 square array with 20-µm base and 400-µm pitch. The two triangular arrays emitted 35 nC in an RF macropulse at 35 MV/m and 13-nC charge at 27 MV/m, respectively, while the sparse array emitted 0.060-nC charge at 15 MV/m. This article presents the results of the triangular array experiments, including damage due to breakdown in the RF gun and initial models of tip-to-tip shielding.

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Perturbation-minimized triangular bunch for high-transformer ratio using a double dogleg emittance exchange beam line

Cited by 26 publications

References 17 publications

Single-shot wakefield measurement system

Single-shot wakefield measurement system

Machine learning for orders of magnitude speedup in multiobjective optimization of particle accelerator systems

Shaped Beams from Diamond Field-Emitter Array Cathodes

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