Space-Charge Modulation in Vacuum Microdiodes at THz Frequencies

Pedersen, Andreas; Manolescu, Andrei; Valfells, Á.

doi:10.1103/physrevlett.104.175002

Cited by 77 publications

(70 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This study is a continuation of earlier work by the authors where a mechanism for bunching of electron beams at the cathode in a vacuum microdiode was discovered through numerical modelling 9 . This bunching occurs in situations where an unlimited supply of electrons is available for emission at the cathode, with negligible emission velocity, in the presence of a constant vacuum field for acceleration.…”

Section: Introductionmentioning

confidence: 52%

Tunability of the terahertz space-charge modulation in a vacuum microdiode

et al. 2013

View full text Add to dashboard Cite

a Corresponding authorUnder certain conditions, space-charge limited emission in vacuum microdiodes manifests as clearly defined bunches of charge with a regular size and interval. The frequency correpsonding to this interval is in the Terahertz range. In this computational study it is demonstrated that, for a range of parameters, conducive to generating THz frequency oscillations, the frequency is dependant only on the cold cathode electric field and on the emitter area. For a planar micro-diode of given dimension, the modulation frequency can be easily tuned simply by varying the applied potential. Simulations of the microdiode are done for 84 different combinations of emitter area, applied voltage and gap spacing, using a molecular dynamics based code with exact Coulomb interaction between all electrons in the vacuum gap, which is of the order 100. It is found, for a fixed emitter area, that the frequency of the pulse train is solely dependent on the vacuum electric field in the diode, described by a simple power law. It is also found that, for a fixed value of the electric field, the frequency increases with diminishing size of the emitting spot on the cathode. Some observations are made on the spectral quality, and how it is affected by the gap spacing in the diode and the initial velocity of the electrons.2

show abstract

Section: Introductionmentioning

confidence: 52%

Tunability of the terahertz space-charge modulation in a vacuum microdiode

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Such oscillations may eventually split the electron beam into bunches if the emission process can be sufficiently fast as in the photoemission case. 13 In our present approach, the diode is initially empty and a large number of electrons can be emitted in the first time steps. In this regime, i.e., for t < 0:01 À 0:02 ps, the space-charge effects are small.…”

Section: -2mentioning

confidence: 99%

Molecular dynamics simulations of field emission from a planar nanodiode

2015

Self Cite

View full text Add to dashboard Cite

High resolution molecular dynamics simulations with full Coulomb interactions of electrons are used to investigate field emission in planar nanodiodes. The effects of space-charge and emitter radius are examined and compared to previous results concerning transition from Fowler-Nordheim to Child-Langmuir current [Y. Y. Lau, Y. Liu, and R. K. Parker, Phys. Plasmas 1, 2082 (1994) and Y. Feng and J. P. Verboncoeur, Phys. Plasmas 13, 073105 (2006)]. The Fowler-Nordheim law is used to determine the current density injected into the system and the Metropolis-Hastings algorithm to find a favourable point of emission on the emitter surface. A simple fluid like model is also developed and its results are in qualitative agreement with the simulations. V C 2015 AIP Publishing LLC. [http://dx.

show abstract

“…Due to the contemporary needs on the studies of nanogaps and short electron bunches, this 1D classical CL law has been extended to various regimes, including multi-dimensions, [3][4][5][6][7] quantum regime, 8,9 short pulse limit, 10,11 single-electron limit, 12 new scaling in other geometries 13 with applications in THz source 14,15 and time dependent current injection. [16][17][18] Electron emission from a sharp tip is important for many applications, such as vacuum microelectronics, 19 compact high current cathodes for high power microwave sources, [20][21][22] ultrafast laser induced electron emission from sharp tip, [23][24][25][26][27] ultrafast electron imaging, [28][29][30] laser-driven dielectric acceleration, 31,32 and high brightness photo-cathode 33,34 for X-ray free electron laser (FEL).…”

Section: Introductionmentioning

confidence: 99%

Space charge limited current emission for a sharp tip

Zhu

Ang

2015

Physics of Plasmas

View full text Add to dashboard Cite

In this paper, we formulate a self-consistent model to study the space charge limited current emission from a sharp tip in a dc gap. The tip is assumed to have a radius in the order of 10s nanometer. The electrons are emitted from the tip due to field emission process. It is found that the localized current density J at the apex of the tip can be much higher than the classical Child Langmuir law (flat surface). A scaling of J / V g 3/2 /D m , where V g is the gap bias, D is the gap size, and m ¼ 1.1-1.2 (depending on the emission area or radius) is proposed. The effects of non-uniform emission and the spatial dependence of work function are presented. V C 2015 AIP Publishing LLC.

show abstract

Space-Charge Modulation in Vacuum Microdiodes at THz Frequencies

Cited by 77 publications

References 10 publications

Tunability of the terahertz space-charge modulation in a vacuum microdiode

Tunability of the terahertz space-charge modulation in a vacuum microdiode

Molecular dynamics simulations of field emission from a planar nanodiode

Space charge limited current emission for a sharp tip

Contact Info

Product

Resources

About