Modeling emission processes in the Finite-Element MICHELLE gun &amp;amp; collector simulation code

Petillo, John; Panagos, Dimitrios; Ovtchinnikov, Serguei; Burke, Alex; Kostas, C.; Jensen, Kevin L.; Levush, B.; Held, Ben; DeFord, J.F.; Nelson, Eric

doi:10.1109/plasma.2010.5534434

Cited by 3 publications

(4 citation statements)

References 4 publications

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“…Such issues are already recognized as a source of difficulty in the proper implementation of the emission equations, particularly those for field emission 12,21 and photoemission. 13 It is argued that the transit time model will be of greater consequence for theoretical photoemission models in development, as photocathode surfaces are flat but have small barriers associated with high quantum efficiency semiconductors (e.g., GaAs, CsK 2 Sb, and CsTe) for which band bending and dipole modifications similar to Eq. (32) affect emission.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…A correlated effect is the introduction of oscillations within the finite-sized emission pulse that have been revealed in Particle-in-Cell, or PIC, simulations explicitly. 13 These effects depend on how close to the cathode edge the launch site of the electron is. In aggregate, a range of transit times will likely contribute to the softening of the sharp transition implied by Eqs.…”

Section: A the Longo Equationmentioning

confidence: 99%

“…8,9 Time-dependent phenomena induced by structure on the beam for which space charge is a contributor or a cause is revealed in numerical simulations and experiments for beam parameters characteristic of accelerators and high frequency microstructures. [10][11][12][13][14][15] Field emission entails additional complications because fields on the order of GV/m are required. Emission is from two dimensional ("knife-edge") and three dimensional ("conical") structures so as to exploit geometrical field enhancement effects for their attainment.…”

Section: Introductionmentioning

confidence: 99%

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Space charge and quantum effects on electron emission

Jensen

Lebowitz

Lau

et al. 2012

Journal of Applied Physics

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Space charge effects reduce electron emission by altering the surface barrier via two effects: increasing the barrier height (Schottky factor) and width to electron emission by lowering the surface field and changing the magnitude of the dipole associated with electron density variation. A one-dimensional emission model using a transit time argument to account for charge in the anode-cathode (AK) gap and an analytical model of the dipole is used to approximate the effects of each factor on the current density. The transit time model is compared to the experimental data of Longo [J. Appl. Phys. 94, 6966 (2003)] for thermal emission. Changes in the dipole contribution are primarily associated with tunneling and therefore field emission. The transit time plus dipole modification is compared to the experimental data of Barbour et al. [Phys. Rev. 92, 45 (1953)] for field emission. The model's application to thermal-field, and photoemission in general is discussed, with the former corresponding to continuous current limit and the latter to a pulsed current limit of the model. V

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: A the Longo Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Space charge and quantum effects on electron emission

Jensen

Lebowitz

Lau

et al. 2012

Journal of Applied Physics

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“…Progress in NRL conducted research activities addressing many of the key issues for achieving significant power, efficiency, linearity, and instantaneous bandwidth in the millimeter and sub-millimeter electromagnetic spectrum will be highlighted. Additional technical details, such as emission physics [3], novel cathodes [4], beam formation [5] and beam transport [6], micro-fabrication techniques [7], novel circuits [8]- [11], numerical analysis of nonlinear beam-wave interaction [12]- [13] and new design codes [14]- [17] are reported at this conference.…”

Section: Discussionmentioning

confidence: 99%

PL-2: Vacuum electronics research perspective at the naval research laboratory

Borsuk¹,

Levush²

2010

2010 IEEE International Vacuum Electronics Conference (IVEC)

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The US Naval Research Laboratory (NRL) is actively engaged in research and development of key technologies for vacuum electronics high-power amplifiers at frequencies ranging from 30 GHz to 1000 GHz. This work includes the development and application of physics-based modeling and simulation tools, the design and development of emittance dominated pencil and spatially distributed electron beams and associated slowwave interaction structures, research on high-currentdensity emitters, the development and application of precise micro-fabrication techniques and thermal management schemes, and the development of metrology techniques in the THz regime. An overview of these activities will be presented, including a discussion of the technological advances required to achieve order-ofmagnitude increases in amplifier performance. A summary of the approaches being pursued and the status of these efforts will also be presented. Future research opportunities for vacuum electronics at NRL will also be discussed.

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