A5103568622- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Gyrotron and Vacuum Electronics Research
- Superconducting Materials and Applications
- Electromagnetic Simulation and Numerical Methods
- Plasma Diagnostics and Applications
- Microwave Engineering and Waveguides
- Electromagnetic Scattering and Analysis
- Laser-Plasma Interactions and Diagnostics
- Spacecraft and Cryogenic Technologies
- Laser Design and Applications
- Engineering Applied Research
- Radiation Effects in Electronics
- Particle Detector Development and Performance
- Antenna Design and Analysis
- Aerodynamics and Fluid Dynamics Research
- Software System Performance and Reliability
- Advanced Data Storage Technologies
- Antenna Design and Optimization
- CCD and CMOS Imaging Sensors
- Superconducting and THz Device Technology
- Full-Duplex Wireless Communications
- Life Cycle Costing Analysis
- Material Properties and Processing
- Soil, Finite Element Methods
SLAC National Accelerator Laboratory
2014-2024
Stanford University
2005-2015
Linac Coherent Light Source
2015
Menlo School
2013
The University of Texas at Austin
2006
Argonne National Laboratory
2001-2003
Southeast University
1992
Recently, there has been some interest in planar or rectangular dielectric accelerating structures for future high-gradient linear accelerators. In this paper, we present a detailed analysis of the modes dielectric-loaded waveguide structure based on circuit model approximation and mode matching method. general, acceleration field synchronous is nonuniform two transverse dimensions. We show, however, that by using series successively rotated 90 degrees, net force can be made almost uniform....
We have successfully designed, fabricated, installed, and tested a super compact $X$-band SLAC Energy Doubler system at SLAC. It is composed of an elegant 3 dB coupler--mode converter--polarizer coupled to single spherical energy storage cavity with high ${Q}_{0}$ 94000 diameter less than 12 cm. The available rf peak power 50 MW can be compressed average more 200 in order double the kick for electron bunches transverse deflector greatly improve measurement resolution both x-ray free-electron...
Field emission from a solid metal surface has been continuously studied for century over macroscopic to atomic scales. It is general knowledge that, other than the properties, emitted current governed solely by applied electric field. A pin cathode used study dependence of field on stored energy in an L-band rf gun. The was changed adjusting axial position (distance between base and gun back surface) while tip kept constant. very strong correlation field-emission with observed. While...
By applying different symmetric boundary conditions, we found that the transverse wakefields generated by an electron bunch traveling through a partially loaded rectangular dielectric structure at off center position can be decomposed into corresponding orthogonal longitudinal section electric (LSE) and magnetic (LSM) modes for guided waves as in case of treated previously. The are characterized using normalized shunt impedance R/Q, function geometry accelerating structure, both LSE LSM...
There is a worldwide interest in developing so-called ultimate storage ring (USR) light sources having electron emittances near the X-ray diffraction limit that would provide spectral brightness one or two orders of magnitude higher than present-day, third-generation and very large coherent flux multi-keV photon energy range [1 Hettel, R. Qin, Q. 2013. Report on Workshop Accelerator R&D for Ultimate Storage Rings, Oct. 30–Nov. 1, 2012, Beijing, China, SLAC-PUB-15379, February [Google...
Developed by SLAC, the advanced computational electromagnetics three-dimensional parallel (ACE3P) code suite is a comprehensive set of finite-element codes for multiphysics modeling particle accelerators. Running on massively computer platforms high fidelity and accuracy simulation, ACE3P enables rapid virtual prototyping accelerator radio frequency (RF) component design, optimization, analysis. Recent advances have been focused implementation numerical algorithms, enhancement capabilities,...
One disadvantage of conventional iris-loaded accelerating structures is the high ratio peak surface electric field to axial useful for a beam. Typically this Es/Ea⩾2. The relative gradient may prove be limitation realizing technologies very accelerators. In article, we present scheme that uses hybrid dielectric and periodic structure reduce Es/Ea near unity, while shunt impedance per unit length r quality factor Q compare favorably with metallic structures. analysis based on MAFIA...
The Linac Coherent Light Source (LCLS) is the first x-ray laser user facility based upon a free electron (FEL). In addition to many other stringent requirements, LCLS XFEL requires extraordinary beam quality saturate at 1.5 angstroms within 100 meter undulator.[1] This new light source using last kilometer of three linac SLAC accelerate an energy as high 13.6 GeV and required gun injector produce very bright for acceleration. At outset project it was recognized that existing RF guns had...
We present a shape optimization method for designing accelerator cavities with large scale computations. The objective is to find the best cavity desired spectral response, such as specified frequencies of resonant modes, field profiles, and external Q values. forward problem Maxwell equation in frequency domain. design parameters are CAD defining shape. develop scalable algorithms discrete adjoint approach use quasi-Newton solve nonlinear problem. Two realistic examples presented.
The LCLS-II linac utilizes superconducting technology operating at continuous wave to accelerate the 1-MHz electron beams 4 GeV produce tunable FELs. TESLA 9-cell cavity is adopted as baseline design for linac. gradient approximately 16 MV/m. highest current 300 µA. Assuming that RF power matched current, optimal loaded QL of found be around 4×10 7 . Because high QL, bandwidth approaches background microphonic detuning, and performance tightly coupled mechanical perturbations...
A simulation workflow has been developed to study dark current (DC) radiation effects using ACE3P and Geant4. The integrated interfaces particle data transfer geometry between the electromagnetic (EM) cavity code Geant4, targeting large-scale problems high-performance computing. process begins by calculating operating mode in vacuum region of an accelerator structure tracking field-emitted electrons influenced EM fields calculated ACE3P. It then transfers at vacuum-wall interface for...
Field emission is strongly coupled to the breakdown problem. A series of experiments being carried out at Argonne Wakefield Accelerator Facility (AWA) using an L-band photocathode gun. Cathodes with different shapes have been tested and a dark current imaging system has set up. Initial experiment results are presented.