Anomalous thermal field emission

25th International Vacuum Nanoelectronics Conference

2012

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New thermal field electron emission energy conversion method for vacuum electron-optical systems (EOS) with a nanostructured surface electron sources is offered and developed. Physical and numerical modeling of an electron emission and transport processes for different EOS is carried out. It is shown that at the specific configuration of electrostatic and magnetic fields in the EOS offered method permits to realize energy conversion processes with high efficiency.

Section: Introductionmentioning

confidence: 99%

New approach to an electron emission thermal-to-electrical energy conversion problem

25th International Vacuum Nanoelectronics Conference

2012

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“…The estimates obtained for v are in quite satisfactory quantitative agreement with the experimental data. The technical possibilities to produce micron and submicron probes with a power density of up to � lOll W/cm 2 and energy of � 1.0-10 ke V based on the new type thermal field emission cathodes [6] with electron reduced brightness of up to � 10 6 A/(cm 2 V sr) are discussed.…”

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confidence: 99%

On a possibility of condensed matter surface profiling by a high brightness electron probes

2010 8th International Vacuum Electron Sources Conference and Nanocarbon

2010

As is known, laser ablation is widely used in time-of-flight mass spectrometry as well as in modem micro-and nanoelectronics, microelectromechanics for structural surface modification and profiling of condensed substances [1,2].In the present work the phenomenon of ablation is treated as a fast process of phase bound-free transition in excited or ionized structural elements (atoms, molecules) of condensed substance exposed to intense corpuscular radiation, in particular, intense electron fluxes. It is known that interaction of a substance with intense either laser or electron beams exhibits some common regular features, which have not yet been interpreted unambiguously. These are the following. 1. The phenomena of laser and electron ablation are of threshold nature, i.e., they appear only when the beam intensity or the electron flux power density (P) exceeds some threshold value (PI) characteristic of a given substance. For a wide range of condensed media, PI � 50 MW/cm 2 [3].2. There is a finite time delay (M ) between the onset of the substance exposure to a concentrated energy flux and the moment of phase transition of the substance to plasma. The time I1t strongly depends on the P level and can widely vary from � 10-8 s (P � PI) to � 10-13 s (at P » PI)The purpose of the present work is to study the physical mechanism of the above features.To calculate the rate of incident radiation energy absorption by a condensed substance (in units of W/m 2 ), we consider the condensed substance as a set of two interrelated subsystems:those of electrons and phonons. Based on the above scheme, we calculate estimates for the thermal conduction flux power density (e) existing in this case. In a one-dimensional approximation, the thermal flux propagating from the surface into the bulk of the substance e , can be expressed as 1where n f is the phonon concentration, V s is the sound velocity, & is the average energy transferred by a phonon at its transition with a local temperature T + I1T to the region with the temperature T. In Debye's approximation, the average phonon energy is defined by the known expreSSIOnwhere N is the concentration of atoms in the substance, k is the Boltzmann constant, Debye temperature, � == % . Integrating (2) in view of (1) yields e � r . N . k(} . � .(2) () is theWhere r = r(�) is a dimensionless parameter whose numerical value is close to r � 0.5 at 978-1-4244-6644-3/10/$26.00 ©2010 IEEE 178

“…For this reason, this phenomenon is known as "low -macroscopic" [2] or "low voltage" field emission (LVE). Now it is established that the basic features of the LVE phenomenon takes place for a wide range of the 2D nanoheterostructures of a kind: conductor-thin dielectric films [1][2][3][4].…”

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confidence: 99%

“…For the LVE excitation it is necessary to "activate" emission process by an external physical impact at NHS substance (by electron (ion) bombardment, high electric field pulse or NHS heating [1,3,4]). …”

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confidence: 99%

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Phenomenological model of the so-called “low voltage” field emission

2014 Tenth International Vacuum Electron Sources Conference (IVESC)

2014

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