Injector for the University of Maryland Electron Ring (UMER)

Kehne, D.; Godlove, Terry F.; Haldemann, P.; Bernal, S.; Guharay, S. K.; Kishek, R. A.; Li, Y.; O’Shea, P.G.; Reiser, M.; Yun, V.; Zou, Y.; Haber, I.

doi:10.1016/s0168-9002(01)00149-8

Cited by 7 publications

(4 citation statements)

References 4 publications

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“…A calculation of intrinsic emittance provides a value of 3.6 m, given the cathode radius and cathode temperature measured by a pyrometer. 8 This number, however, proved inconsistent with some of the measurements. For example, the beam size from transport experiments in the injector hinted at a much larger emittance ͑ϳ12-15 m͒.…”

Section: Shadow Of Anode Gridmentioning

confidence: 89%

“…The electron gun is of Pierce geometry with a 4 mm radius cathode. 8 Changing the A/K separation or the gridcathode potential can vary the perveance. Since the accelerating potential across the gap is applied using a dc 10 kV power supply, a grid located 0.15 mm from the cathode surface is biased negatively ͑usually at 40-50 V͒ in order to impede the current flow until a positive pulse is applied to the grid.…”

Section: B the Umer Electron Gunmentioning

confidence: 99%

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Simulations and experiments with space-charge-dominated beams

et al. 2003

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Beams in which space charge forces are stronger than the force from thermal pressure are nonneutral plasmas, since particles interact mostly via the long-range collective potential. An ever-increasing number of applications demand such high-brightness beams. The University of Maryland Electron Ring ͓P. G. O'Shea et al., Nucl. Instrum Methods Phys. Res. A 464, 646 ͑2001͔͒, currently under construction, is designed for studying the physics of space-charge-dominated beams. Indirect ways of measuring beam emittance near the UMER source produced conflicting results, which were resolved only when a direct measurement of phase space indicated a hollow velocity distribution. Comparison to self-consistent simulation using the particle-in-cell code WARP ͓D. P. Grote et al., 193 ͑1996͔͒ revealed sensitivity to the initial velocity distribution. Since the beam is born with nonuniformities and granularity, dissipation mechanisms and rates are of interest. Simulations found that phase mixing by means of chaotic particle orbits is possible in certain situations, and proceeds much faster than Landau damping. The implications for using beams to model other N-body systems are discussed.

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Section: Shadow Of Anode Gridmentioning

confidence: 89%

Section: B the Umer Electron Gunmentioning

confidence: 99%

Simulations and experiments with space-charge-dominated beams

et al. 2003

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“…The design of the electron gun and simulations of its performance are described elsewhere~Haber et al, 2001; Kehne et al, 2001!. A grid near the cathode can be used to generate perturbations as a means of investigating instabilities. In addition, we have been investigating the possibility of producing ultrashort~1 ns!…”

Section: Umer Design Featuresmentioning

confidence: 99%

Experiments with space-charge-dominated beams for heavy ion fusion applications

et al. 2002

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A detailed understanding of the physics of space-charge-dominated beams is vital in the design of heavy ion inertial fusion~HIF! drivers. In that regard, low-energy, high-intensity electron beams provide an excellent model system. The University of Maryland Electron Ring~UMER!, currently being installed, has been designed to study the physics of space-charge-dominated beams with extreme intensity in a strong focusing lattice with dispersion. At 10 keV and 100 mA, the beam from the UMER injector has a generalized perveance as much as 0.0015, corresponding to that of proposed HIF drivers. Though compact~11 m in circumference!, UMER will be a very complex device by the time of its completion~expected 2003!. We present an update on the construction as well as recent experimental results.

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“…The design of the electron gun and simulations of its performance are described elsewhere [11,12]. It employs a commercial 8-mm diameter dispenser cathode with integral filament and grid.…”

Section: Gun and Injectormentioning

confidence: 99%

The University Maryland Electron Ring (UMER)

O'Shea

Reiser

Kishek

et al. 2001

Nuclear Instruments and Methods in Physics Research Section A:

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A detailed understanding of the physics of space-charge dominated beams is vital for many advanced accelerators that desire to achieve high beam intensity. In that regard, low-energy, high-intensity electron beams provide an excellent model system. The University of Maryland Electron ring (UMER), currently under construction, has been designed to study the physics of space-charge dominated beams with extreme intensity in a strong focusing lattice with dispersion. The tune shift in UMER will be more than an order of magnitude greater than exiting synchrotrons and rings. The 10-keV, 100 mA, UMER beam has a generalized perveance in the range of 0.0015, and a tune shift of 0.9. Though compact (11-m in circumference), UMER is a very complex device, with over 140 focusing and bending magnets. We report on the unique design features of this research facility, the beam physics to be investigated, and early experimental results.

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Injector for the University of Maryland Electron Ring (UMER)

Cited by 7 publications

References 4 publications

Simulations and experiments with space-charge-dominated beams

Simulations and experiments with space-charge-dominated beams

Experiments with space-charge-dominated beams for heavy ion fusion applications

The University Maryland Electron Ring (UMER)

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