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A list of all the posts and pages found on the site. For you robots out there is an XML version available for digesting as well.
Pages
About me
About me
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Teaching experience 1
Undergraduate course, University 1, Department, 2014
Teaching experience 2
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Posts
Future Blog Post
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Blog Post number 4
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This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
Blog Post number 3
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This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
Blog Post number 2
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This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
Blog Post number 1
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This is a sample blog post. Lorem ipsum I can’t remember the rest of lorem ipsum and don’t have an internet connection right now. Testing testing testing this blog post. Blog posts are cool.
portfolio
Portfolio item number 1
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Portfolio item number 2
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publications
FARSIGHT
A Forward Adaptively Refined and Regularized Semi-Lagrangian Integral GPU- and Hierarchical Tree-code-accelerated method for the Vlasov-Poisson system.
Recommended citation: (in preparation) R.T. Sandberg, A.G.R. Thomas, and R. Krasny. "FARSIGHT: A Forward Adaptively Refined and Regularized Semi-Lagrangian Integral GPU- and Hierarchical Tree-code-accelerated method for the Vlasov-Poisson system."
Photon Acceleration from Optical to XUV
Published in unknown, 2023
Frequency upshift of a laser pulse in wake of relativistic electron beam.
Recommended citation: R.T. Sandberg, and A.G.R. Thomas. "Photon Acceleration from Optical to XUV."
talks
Numerical finite particle effects and wave breaking limits
Published:
Seminal works of Dawson, Akhiezer and Polovin, and Coffey provide theoretical cold, relativistic, and warm wave breaking limits, respectively. There is renewed interest in understanding wave breaking limits to either achieve or avoid them, depending on the injection and acceleration mechanism. Numerical simulations are often used to investigate breaking limits. When particle methods are used, they commonly employ finite numerical particle size or, equivalently, a smoothed Green’s function for the electric interaction. In this work we present studies of finite numerical particle effects on wave breaking limits. We discuss phase mixing times and breaking limits in relativistic and non relativistic cases when using finite sized numerical particles in simulation. We compare PIC models with the Dawson sheet model and other particle methods, using a 1d grid-free particle method employing a smoothed kernel.
FARRSIGHT: A Forward Adaptively Refined and Regularized Semi-Lagrangian Integral Green’s function Hierarchical Tree-code accelerated method for the Vlasov-Poisson system
Published:
In this talk we present a new forward semi-Lagrangian particle method for the Vlasov-Poisson (VP) system. Recent methods for solving the VP system include deformable particles and high-order and/or discontinuous-Galerkin Eulerian methods. In contrast to these, we do not use any operator splitting and obtain the electric field by summing regularized pairwise particle interactions using a hierarchical treecode. We use remeshing and adaptive mesh refinement to maintain an efficient representation of phase space. We benchmark on several standard test cases including Landau damping and the two-stream instability.
FARRSIGHT: A Forward Adaptively Refined and Regularized Semi-Lagrangian Integral GPU- and Hierarchical Treecode-Accelerated Method for the Vlasov-Poisson System
Published:
In this talk we present a new forward semi-Lagrangian particle method for the Vlasov-Poisson (VP) system. Recently developed methods for the VP system include deformable particles and high-order or discontinuous-Galerkin Eulerian methods. In contrast to these, we do not use any operator splitting and obtain the electric field by summing regularized pairwise particle interactions using a GPU-accelerated tree-code. We remesh and use adaptive mesh refinement to maintain an efficient representation of phase space. We benchmark on several standard test cases including Landau damping and the two-stream instability. We also compare the multi-threaded and single-GPU performance of the method.
Phase matched plasma wakefield photon acceleration
Published:
We present Phase Matched Plasma Wakefield Photon Acceleration (PMPA), a scheme for dephasingless photon acceleration in a particle-beam-driven wake.
Electromagnetic radiation seeing a decreasing plasma gradient shifts up in frequency.
In PMPA, a laser pulse is situated in the wake of a relativistic electron bunch so that it sees a decreasing density gradient.
Using a tapered density profile to keep witness laser pulse at the phase in the wake where the density is decreasing, simulations suggest that the frequency of the witness pulse can be shifted up by a factor of 5-10.
teaching
Undergraduate teaching experience
Tutor, Brigham Young University, Mathematics Department, 2010
Tutored undergraduate mathematics 6 semesters, from 2010 to 2013
Teaching experience at BYU
Graduate student instructor, Brigham Young University, Department of Mathematics, 2013
Taught 5 semesters, several different undergraduate courses
Teaching experience at Michigan
Graduate student instructor, University of Michigan, Department of Mathematics, 2015
Taught 6 semesters at University of Michigan