IPAC2018 - List of Authors (Nasr, M.H.)

Paper	Title	Page
THPAL080	Parallel-Feed SRF Accelerator Structures	3835
	P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. Development of SRF accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed NCRF structure at SLAC has served as a proof-of-concept. Applied to SRF, such a structure could dramatically reduce power consumption while boosting the achievable gradient. Instead of coupled elliptical cells, our structure employs isolated reentrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Such a structure has been fabricated from bulk Cu and tested at SLAC - designed for X-band, it operates at a record gradient of 150 MV/m. Adapting to SRF at 1.3 GHz and fabricating from Nb, such a cavity could achieve more than 50% lower RF loss and 40% higher gradient compared to the TESLA cavity. We will describe our simulations and propose an experimental roadmap for demonstrating this technology.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL080
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THPMK048	The Design and Construction of a Novel Dual-Mode Dual-Frequency Linac Design	4391
SUSPF045	use link to see paper's listing under its alternate paper code
	M.H. Nasr, S.G. Tantawi SLAC, Menlo Park, California, USA
	One promising approach in boosting accelerators efficiency is dual-mode simultaneous operation. In our work, the topic of dual-mode acceleration is studied from a wider perspective with new approaches and tools. We present a new type of accelerator structures that operates simultaneously with two modes and two frequencies. The frequencies are not constrained to be harmonically related, but rather have a common sub-harmonic. These designs will utilize a newly developed parallel-feeding network that feeds each individual accelerating cell independently using a distributed feeding network. As a result, the design problem converges to a single-cell design with identical cells. The cells are designed for maximum efficiency using new geometrical optimization that utilizes nonuniform rational B-spline (NURBS) with a series of control points. We will present a study on the topic for S-band simultaneous operation with C-band or X-band.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK048
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THPMK049	New Geometrical-Optimization Approach using Splines for Enhanced Accelerator Cavities' Performance	4395
	M.H. Nasr, S.G. Tantawi SLAC, Menlo Park, California, USA
	Over the past decades accelerator scientists made a huge effort in advancing the technology of particle accelerators, which lead to state-of-the-art fabrication techniques as well as simulation tools. Combining these advancements with the large boosting in computing speed provides large flexibility and motivation to investigate new accelerator geometries. In this paper, we describe a new optimization approach for the geometry of accelerating cells. This approach uses a set of control points with variable positions to control a non-uniform rational B-spline (NURBS), which describes the cavity shape. The positions of the control points are then optimized using differential-evolution optimization to maximize/minimize a defined optimization function, which is defined by the user and depends on the cavity parameters such as the shunt impedance, wall losses, peak surface fields…etc. This optimization approach leads to accelerator geometries with enhanced performance and very smooth surface fields.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK049
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Paper

Title

Page

Parallel-Feed SRF Accelerator Structures

3835

P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
Development of SRF accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed NCRF structure at SLAC has served as a proof-of-concept. Applied to SRF, such a structure could dramatically reduce power consumption while boosting the achievable gradient. Instead of coupled elliptical cells, our structure employs isolated reentrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Such a structure has been fabricated from bulk Cu and tested at SLAC - designed for X-band, it operates at a record gradient of 150 MV/m. Adapting to SRF at 1.3 GHz and fabricating from Nb, such a cavity could achieve more than 50% lower RF loss and 40% higher gradient compared to the TESLA cavity. We will describe our simulations and propose an experimental roadmap for demonstrating this technology.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK048

The Design and Construction of a Novel Dual-Mode Dual-Frequency Linac Design

4391

SUSPF045

use link to see paper's listing under its alternate paper code

M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

One promising approach in boosting accelerators efficiency is dual-mode simultaneous operation. In our work, the topic of dual-mode acceleration is studied from a wider perspective with new approaches and tools. We present a new type of accelerator structures that operates simultaneously with two modes and two frequencies. The frequencies are not constrained to be harmonically related, but rather have a common sub-harmonic. These designs will utilize a newly developed parallel-feeding network that feeds each individual accelerating cell independently using a distributed feeding network. As a result, the design problem converges to a single-cell design with identical cells. The cells are designed for maximum efficiency using new geometrical optimization that utilizes nonuniform rational B-spline (NURBS) with a series of control points. We will present a study on the topic for S-band simultaneous operation with C-band or X-band.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK049

New Geometrical-Optimization Approach using Splines for Enhanced Accelerator Cavities' Performance

4395

M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

Over the past decades accelerator scientists made a huge effort in advancing the technology of particle accelerators, which lead to state-of-the-art fabrication techniques as well as simulation tools. Combining these advancements with the large boosting in computing speed provides large flexibility and motivation to investigate new accelerator geometries. In this paper, we describe a new optimization approach for the geometry of accelerating cells. This approach uses a set of control points with variable positions to control a non-uniform rational B-spline (NURBS), which describes the cavity shape. The positions of the control points are then optimized using differential-evolution optimization to maximize/minimize a defined optimization function, which is defined by the user and depends on the cavity parameters such as the shunt impedance, wall losses, peak surface fields…etc. This optimization approach leads to accelerator geometries with enhanced performance and very smooth surface fields.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)