The University of Maryland Electron Ring Program

Kishek, R. A.; Beaudoin, B.; Bernal, S.; Cornacchia, M.; Feldman, D. W.; Fiorito, R.; Haber, I.; Koeth, T.; Mo, Yifei; O’Shea, P.G.; Řežaei, K.Poor; Sutter, David; Zhang, H.D.

doi:10.1016/j.nima.2013.05.062

Cited by 10 publications

(2 citation statements)

References 22 publications

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“…UMER is a scaled, 10 keV (β = 0.195) electron ring experiment for the study of high-intensity beam dynamics relevant to higher-energy ion rings. A range of space charge densities are selected by aperturing the beam near the source, in the range ν/ν 0 = 0.95 to 0.14 for nominal tune 6.7 (incoherent shifts ∆ν = 0.3 to 5.7) [9,10]. As such, typical operation in UMER exceeds the space charge intensity of existing, production-level rings such as ν/ν 0 = 0.98, ∆ν = 0.15 in the SNS accumulator ring [11].…”

Section: Umer Programmentioning

confidence: 99%

Single-invariant nonlinear optics for a small electron recirculator

Ruisard

Komkov

Beaudoin

et al. 2019

Phys. Rev. Accel. Beams

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This paper describes the design and simulation of a proof-of-concept quasi-integrable octupole lattice at the University of Maryland Electron Ring (UMER). This experiment tests the feasibility of nonlinear integrable optics, a novel technique that is expected to mitigate resonant beam loss and enable low-loss high-intensity beam transport in rings. Integrable lattices with large amplitudedependent tune spreads, created by nonlinear focusing elements, are proposed to damp beam response to resonant driving perturbations while maintaining large dynamic aperture [Danilov and Nagaitsev, PRSTAB, 2010]. At UMER, a lattice with a single octupole insert is designed to test the predictions of this theory. The planned experiment employs a low-current high-emittance beam with low space charge tune shift (∼ 0.005) to probe the dynamics of a lattice with large externally-induced tune spread. Design studies show that a lattice composed of a 25-cm octupole insert and existing UMER optics can induce a tune spread of ∼ 0.13. Stable transport is observed in PIC simulation for many turns at space charge tune spread 0.008. A maximum spread of ∆ν = 0.11 (RMS 0.015) is observed for modest octupole strength (peak 50 T /m 3 ). A simplified model of the system explores beam sensitivity to steering and focusing errors. Results suggest that control of orbit distortion to < 0.2 mm within the insert region is essential. However, we see only weak dependence on deviations of lattice phase advance (≤ 0.1 rad.) from the invariant-conserving condition.

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Section: Umer Programmentioning

confidence: 99%

Single-invariant nonlinear optics for a small electron recirculator

Ruisard

Komkov

Beaudoin

et al. 2019

Phys. Rev. Accel. Beams

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“…Using a low energy electron beam to simulate space charge dominated ion beams and to study the resistive wall instability have become a major endeavor at the University of Maryland at College Park. 32,275,276 Significant progress concerning halo formation, evolution of x-y phase space, emittance growth, and resistive instabilities, etc., has been made. These achievements have been summarized by Reiser 277 and by Kishek et al 276 It is noteworthy that this university scale effort provided the much needed benchmark between experiments, theory, and simulation codes in space charge dominated beams, in addition to pushing into a space charge regime that is unprecedented in the HIF community.…”

Section: B Heavy Ion Beamsmentioning

confidence: 99%

100 years of the physics of diodes

Zhang

Valfells

Ang

et al. 2017

Applied Physics Reviews

188

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The Child-Langmuir Law (CL), discovered a century ago, gives the maximum current that can be transported across a planar diode in the steady state. As a quintessential example of the impact of space charge shielding near a charged surface, it is central to the studies of high current diodes, such as high power microwave sources, vacuum microelectronics, electron and ion sources, and high current drivers used in high energy density physics experiments. CL remains a touchstone of fundamental sheath physics, including contemporary studies of nanoscale quantum diodes and nano gap based plasmonic devices. Its solid state analog is the Mott-Gurney law, governing the maximum charge injection in solids, such as organic materials and other dielectrics, which is important to energy devices, such as solar cells and light emitting diodes. This paper reviews the important advances in the physics of diodes since the discovery of CL, including virtual cathode formation and extension of CL to multiple dimensions, to the quantum regime, and to ultrafast processes. We review the influence of magnetic fields, multiple species in bipolar flow, electromagnetic and time dependent effects in both short pulse and high frequency THz limits, and single electron regimes. Transitions from various emission mechanisms (thermionic-, field-, and photoemission) to the space charge limited state (CL) will be addressed, especially highlighting the important simulation and experimental developments in selected contemporary areas of study. We stress the fundamental physical links between the physics of beams to limiting currents in other areas, such as low temperature plasmas, laser plasmas, and space propulsion.

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Inertial Confinement Fusion—Experimental Physics: Heavy Ion Beam Drive

Seidl¹

2021

Encyclopedia of Nuclear Energy

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The University of Maryland Electron Ring Program

Cited by 10 publications

References 22 publications

Single-invariant nonlinear optics for a small electron recirculator

Single-invariant nonlinear optics for a small electron recirculator

100 years of the physics of diodes

Inertial Confinement Fusion—Experimental Physics: Heavy Ion Beam Drive

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