IPAC2018 - List of Authors (Hall, C.C.)

Paper	Title	Page
MOPML060	Self-Consistent Simulation and Optimization of Space-Charge Limited Thermionic Energy Converters	543
	N.M. Cook, J.P. Edelen, C.C. Hall RadiaSoft LLC, Boulder, Colorado, USA J.-L. Vay LBNL, Berkeley, California, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0017162. Thermionic energy converters (TEC) are an attractive technology for modular, efficient transfer of heat to electrical energy. The steady-state dynamics of a TEC are a function of the emission characteristics of the cathode and anode, an array of intra-gap electrodes and dielectric structures, and the self-consistent dynamics of the electrons in the gap. Proper modeling of these devices requires self-consistent simulation of the electron interactions in the gap. We present results from simulations of these devices using the particle-in-cell code Warp, developed at Lawrence Berkeley National Lab. We consider the role of individual energy loss mechanisms in reducing device efficiency, including kinetic losses, radiative losses, and dielectric charging. We discuss the implementation of an external circuit model to provide realistic feedback. Lastly, we illustrate the potential to use nonlinear optimization to maximize the efficiency of these devices by examining grid transparency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML060
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THPAK082	Simulation of Perturbative Effects in IOTA	3422
	C.C. Hall, D.L. Bruhwiler, N.M. Cook, J.P. Edelen, S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA
	The Integrable Optics Test Accelerator (IOTA) is being commissioned at Fermi National Laboratory for study of the concept of nonlinear integrable optics. The use of a special nonlinear magnetic element introduces large tune spread with amplitude while constraining the idealized dynamics by two integrals of motion. The nonlinear element should provide suppression of instabilities through nonlinear decoherence. We examine the case of a bunch injected off-axis and the resulting damping of centroid oscillations from decoherence. A simple model of the damping is described and compared to simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK082
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THPAK083	An s-Based Symplectic Spectral Space Charge Algorithm	3425
	N.M. Cook, D.T. Abell, D.L. Bruhwiler, J.P. Edelen, C.C. Hall, S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC001340. Traditional finite-difference particle-in-cell methods for modeling self-consistent space charge introduce non-Hamiltonian effects that make long-term tracking in storage rings unreliable. Foremost of these is so-called grid heating. Particularly for studies where the Hamiltonian invariants are critical for understanding the beam dynamics, such as nonlinear integrable optics, these spurious effects make interpreting simulation results difficult. To remedy this, we present a symplectic spectral space charge algorithm that is free of non-Hamiltonian numerical effects and, therefore, suitable for long-term tracking studies. We present initial results demonstrating the implementation of the algorithm, using a spectral representation of the fields and macro particles to preserve Hamiltonian structures. We then discuss applications to the Integrable Optics Test Accelerator (IOTA), currently under construction at Fermilab.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK083
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Paper

Title

Page

Self-Consistent Simulation and Optimization of Space-Charge Limited Thermionic Energy Converters

543

N.M. Cook, J.P. Edelen, C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
J.-L. Vay
LBNL, Berkeley, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0017162.
Thermionic energy converters (TEC) are an attractive technology for modular, efficient transfer of heat to electrical energy. The steady-state dynamics of a TEC are a function of the emission characteristics of the cathode and anode, an array of intra-gap electrodes and dielectric structures, and the self-consistent dynamics of the electrons in the gap. Proper modeling of these devices requires self-consistent simulation of the electron interactions in the gap. We present results from simulations of these devices using the particle-in-cell code Warp, developed at Lawrence Berkeley National Lab. We consider the role of individual energy loss mechanisms in reducing device efficiency, including kinetic losses, radiative losses, and dielectric charging. We discuss the implementation of an external circuit model to provide realistic feedback. Lastly, we illustrate the potential to use nonlinear optimization to maximize the efficiency of these devices by examining grid transparency.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML060

Export •

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

THPAK082

Simulation of Perturbative Effects in IOTA

3422

C.C. Hall, D.L. Bruhwiler, N.M. Cook, J.P. Edelen, S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA

The Integrable Optics Test Accelerator (IOTA) is being commissioned at Fermi National Laboratory for study of the concept of nonlinear integrable optics. The use of a special nonlinear magnetic element introduces large tune spread with amplitude while constraining the idealized dynamics by two integrals of motion. The nonlinear element should provide suppression of instabilities through nonlinear decoherence. We examine the case of a bunch injected off-axis and the resulting damping of centroid oscillations from decoherence. A simple model of the damping is described and compared to simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK082

Export •

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

THPAK083

An s-Based Symplectic Spectral Space Charge Algorithm

3425

N.M. Cook, D.T. Abell, D.L. Bruhwiler, J.P. Edelen, C.C. Hall, S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC001340.
Traditional finite-difference particle-in-cell methods for modeling self-consistent space charge introduce non-Hamiltonian effects that make long-term tracking in storage rings unreliable. Foremost of these is so-called grid heating. Particularly for studies where the Hamiltonian invariants are critical for understanding the beam dynamics, such as nonlinear integrable optics, these spurious effects make interpreting simulation results difficult. To remedy this, we present a symplectic spectral space charge algorithm that is free of non-Hamiltonian numerical effects and, therefore, suitable for long-term tracking studies. We present initial results demonstrating the implementation of the algorithm, using a spectral representation of the fields and macro particles to preserve Hamiltonian structures. We then discuss applications to the Integrable Optics Test Accelerator (IOTA), currently under construction at Fermilab.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK083

Export •

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